Large Cell Neuroendocrine Carcinoma

Neoplastic MONDO:0005057 Pathograph 22 Show in embeddings browser Neuroendocrine Carcinoma

Large cell neuroendocrine carcinoma (LCNEC) is a rare, high-grade, poorly differentiated neuroendocrine carcinoma composed of large malignant epithelial cells that combine neuroendocrine morphology (organoid nesting, palisading, rosettes) with immunohistochemically demonstrable neuroendocrine differentiation, a high mitotic rate and extensive necrosis. The lung is the prototype and best-studied site, where LCNEC accounts for roughly 1-3% of lung cancers and arises almost exclusively in older heavy smokers, but the entity is also recognised at many extrapulmonary sites. Genomically LCNEC is not one disease: near-universal TP53 inactivation is followed by a bifurcation into a TP53+RB1 co-altered (SCLC-like, or type II) group and a STK11/KEAP1-altered (NSCLC-like, or type I) group, which are largely mutually exclusive and which differ in neuroendocrine transcriptional programme and in chemotherapy outcome. Clinically LCNEC behaves like non-small cell lung cancer at stages I-III and like small cell lung cancer at stage IV, and prognosis is poor.

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1
Mappings
11
Pathophys.
1
Histopath.
2
Phenotypes
2
Gaps
22
Pathograph
5
Genes
5
Medical Actions
6
Subtypes
2
Differentials
1
Models
2
References
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Deep Research
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Mappings

MONDO
MONDO:0005057 large cell neuroendocrine carcinoma
skos:exactMatch
◆

Subtypes

6
Pulmonary large cell neuroendocrine carcinoma MONDO:0003960
LCNEC arising in the lung. The prototype and by far the best-characterised form; essentially all of the genomic subtyping and chemotherapy-outcome literature curated in this entry derives from pulmonary cohorts.
Show evidence (1 reference)
PMID:29535388 SUPPORT Human Clinical
"LCNECs account for 2–3% of all resected lung cancers and belong to the category of neuroendocrine lung tumors"
Establishes the pulmonary form as a defined entity within neuroendocrine lung tumours.
Lung combined large cell neuroendocrine carcinoma MONDO:0004142
Pulmonary LCNEC admixed with a non-neuroendocrine component (adenocarcinoma or squamous cell carcinoma) or with small cell carcinoma. Notably the RB1 alterations of the LCNEC component are frequently shared with the combined component, arguing for a common clonal origin rather than collision tumours.
Show evidence (1 reference)
PMID:29535388 SUPPORT Human Clinical
"Nineteen of 75 LCNECs included in this study showed additional histological components of lung adenocarcinoma (ADC) (n = 2), squamous cell carcinoma (SqCC) (n = 5) or SCLC (n = 12)"
Quantifies the combined histology subtype within a genomically characterised LCNEC cohort.
Thymic large cell neuroendocrine carcinoma MONDO:0003047
LCNEC arising in the thymus, the highest-grade member of the thymic neuroendocrine tumour family. Curated in depth in `kb/disorders/Thymic_Neuroendocrine_Carcinoma.yaml`; listed here only to make the site spectrum complete.
Cervical large cell neuroendocrine carcinoma MONDO:0006138
LCNEC arising in the uterine cervix, one of the recognised gynaecological high-grade neuroendocrine carcinomas. Unlike the smoking-driven pulmonary form, cervical LCNEC is associated with high-risk HPV. A reported HPV18-positive case also showed a very low tumour mutational burden (1.21/Mb), the opposite of the high TMB that characterises pulmonary LCNEC - a concrete reason not to generalise the pulmonary mechanism or the pulmonary immunotherapy rationale across sites. That is a single case, so it is recorded here as a caution rather than an established site difference.
Show evidence (1 reference)
PMID:42521492 SUPPORT Human Clinical
"Biopsy showed chromogranin A and synaptophysin positivity, diffuse p16, and Ki-67%~80%."
Documents an HPV18-positive cervical LCNEC with the defining neuroendocrine marker profile and high proliferation index. Curated as PARTIAL because this is a single case report.
Pancreatic large cell neuroendocrine carcinoma MONDO:0006347
LCNEC arising in the pancreas, within the poorly differentiated pancreatic neuroendocrine carcinoma group.
Breast large cell neuroendocrine carcinoma MONDO:0003959
LCNEC arising in the breast, a rare high-grade neuroendocrine breast carcinoma.
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Discussions and Knowledge Gaps

2
Does the type I / type II (or SCLC-like / NSCLC-like) molecular classification of LCNEC hold up as a binary, and should it direct first-line therapy prospectively?
KNOWLEDGE GAP lcnec_molecular_subtype_binary
Attached to
pathophysiology#RB1 Biallelic Inactivation pathophysiology#STK11 and KEAP1 Biallelic Inactivation
The subgroup framework rests on retrospective cohorts, and the one treatment-relevant finding (RB1 wild-type tumours doing better with NSCLC-type than with SCLC-type chemotherapy) comes from a registry analysis, not a randomised trial. The two branches are reported as mutually exclusive in 82% of cases, which leaves a substantial residue that fits neither, and the discordance between the genomic label and the transcriptional phenotype suggests a continuum of neuroendocrine differentiation rather than two classes. The largest clinical genomic series to date makes the residue explicit: of 1,426 profiled LCNEC samples, 557 were SCLC-like, 530 NSCLC-like, 25 carcinoid-like and 314 could not be classified at all. No prospective biomarker-stratified trial has yet tested assigning chemotherapy by RB1 status.
Proposed experiments
Prospective RB1-stratified chemotherapy trial in advanced LCNEC
lcnec_rb1_stratified_chemotherapy_trial
Randomise patients with advanced LCNEC to platinum-etoposide versus platinum plus gemcitabine or taxane, stratified prospectively by RB1 mutation and Rb immunohistochemistry, with overall survival as the primary endpoint.
Show evidence (1 reference)
PMID:38159439 SUPPORT Human Clinical
"Under this schema, 530 samples were classified as NSCLC-like and 314 remained unclassified."
Quantifies the proportion of LCNEC that does not fit either genomic subtype, which is the empirical basis for treating the binary as incomplete.
How much of the reported epidemiology of LCNEC is distorted by under-diagnosis on biopsy material?
KNOWLEDGE GAP lcnec_underdiagnosis_epidemiology
Attached to
pathophysiology#Neuroendocrine Lineage Programme Expression
Neuroendocrine morphology is absent in roughly half of biopsies from tumours that prove to be LCNEC on resection, and registry-coded frequency (0.9% of lung cancers) is well below the pathology-reviewed estimate (about 3%). Population statistics on incidence, stage distribution and survival are therefore drawn from a systematically incomplete and probably resection-biased case set, and the apparent rise in incidence may partly reflect improving recognition rather than changing biology.
Proposed experiments
Central pathology re-review of a population-based lung cancer cohort
lcnec_population_pathology_rereview
Apply the validated two-of-three neuroendocrine immunohistochemistry rule to a consecutive population-based series of non-small cell lung cancers without obvious squamous or glandular differentiation, and compare the resulting LCNEC frequency and stage distribution against registry codes.
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Pathophysiology

11
Tobacco Carcinogen Exposure and Smoking-Associated Mutagenesis
Pulmonary LCNEC arises almost exclusively in older heavy smokers. Whole-exome and whole-genome sequencing shows a high exonic mutation rate dominated by C:G>A:T transversions and by COSMIC mutational signature 4, the canonical tobacco-carcinogen signature. This mutagenic burden is what generates the tumour-suppressor loss-of-function events that define both molecular subgroups.
Downstream
TP53 Inactivation Carcinogen-induced mutagenesis produces the near-universal TP53 loss-of-function events that initiate the LCNEC pathograph.
Show evidence (2 references)
PMID:29535388 SUPPORT Human Clinical
"On average, LCNECs exhibited an exonic mutation rate of 8.6 non-synonymous mutations per million base pairs and a C:G > A:T transversion rate of 38.7%"
Quantifies the tobacco-type mutational burden in a genomically profiled LCNEC cohort.
PMID:29535388 SUPPORT Human Clinical
"LCNEC and SCLC are clinically aggressive tumors presenting in elderly heavy-smokers"
Establishes heavy smoking as the near-universal clinical context of LCNEC.
TP53 Inactivation
Biallelic TP53 loss of function is the near-universal first hit in LCNEC, reported in 78% of tumours by targeted sequencing and 92% by whole-exome sequencing. Loss of p53 abrogates DNA-damage checkpoint control and apoptosis, licensing both the genomic instability and the second-hit bifurcation that follow.
TP53 hgnc:11998 HUGO Gene Nomenclature Committee (hgnc) Relation: this pathophysiological event involves this gene This pathophysiological event involves TP53 (hgnc:11998). hgnc:11998 is a gene from the HUGO Gene Nomenclature Committee.
Downstream
Mutator Phenotype and Chromosomal Instability Loss of p53-dependent damage surveillance permits accumulation of mutations and copy-number change.
RB1 Biallelic Inactivation TP53 loss is co-selected with RB1 loss in the SCLC-like/type II branch; the two are reported as co-mutated rather than sequentially causal.
STK11 and KEAP1 Biallelic Inactivation In the alternative branch TP53 loss is accompanied by STK11 and/or KEAP1 inactivation rather than by RB1 loss.
Show evidence (2 references)
PMID:26960398 SUPPORT Human Clinical
"Commonly altered genes in LCNEC included TP53 (78%), RB1 (38%), STK11 (33%), KEAP1 (31%), and KRAS (22%)"
Gives the mutation frequency of TP53 and of the genes defining the downstream branches.
PMID:29535388 SUPPORT Human Clinical
"TP53 was the most frequently mutated gene (92%)"
Independent whole-exome confirmation that TP53 loss is near universal.
Mutator Phenotype and Chromosomal Instability
Following p53 loss, LCNEC accumulates a high mutation burden together with recurrent focal amplifications (MYCL1 at 1p34, FGFR1 at 8p12, MYC at 8q24.21, NKX2-1 at 14q13) and deletions (CDKN2A at 9p21), i.e. the mutator phenotype and chromosomal instability that the genome-instability module describes.
DNA repair GO:0006281 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves decreased DNA repair (GO:0006281). GO:0006281 is a biological process from the Gene Ontology. ↓ DECREASED
Downstream
High-Grade Proliferative Activity and Necrosis Accumulated driver alterations converge on the high-grade proliferative phenotype.
Show evidence (2 references)
PMID:29535388 SUPPORT Human Clinical
"Analyses of chromosomal gene copy numbers revealed statistically significant amplifications of 1p34 (containing the MYCL1 gene, 12%), 8p12 (containing FGFR1, 7%), 8q24.21 (containing MYC, 5%)"
Documents the recurrent copy-number changes that constitute chromosomal instability in LCNEC.
PMID:35641209 SUPPORT Human Clinical
"Large cell neuroendocrine carcinoma (12.7 mutations/Mb) and SCLC (11.9 mutations/Mb) showed higher tumor mutational burdens than TC (2.4 mutations/Mb) and AC (7.1 mutations/Mb)"
Quantifies the mutator phenotype, showing that LCNEC carries a tumour mutational burden comparable to SCLC and several-fold above the low- and intermediate-grade carcinoids.
RB1 Biallelic Inactivation
Biallelic RB1 inactivation, co-occurring with TP53 loss, defines the SCLC-like (Rekhtman) or type II (George) subgroup. RB1 mutation is reported in 38-47% of cases and loss of nuclear Rb protein in up to 72%. This branch is mutually exclusive with the STK11/KEAP1 branch. Note the counterintuitive transcriptional consequence: despite the SCLC-like genotype, type II tumours show reduced neuroendocrine marker expression.
RB1 hgnc:9884 HUGO Gene Nomenclature Committee (hgnc) Relation: this pathophysiological event involves this gene This pathophysiological event involves RB1 (hgnc:9884). hgnc:9884 is a gene from the HUGO Gene Nomenclature Committee.
Downstream
Loss of G1/S Cell-Cycle Checkpoint Control Loss of the Rb brake releases the G1/S restriction point.
NOTCH Pathway Dysregulation Type II (RB1-altered) tumours display a NOTCH-high, neuroendocrine-low transcriptional state; the mechanistic link between RB1 loss and NOTCH activity in LCNEC is correlative rather than established.
Show evidence (4 references)
PMID:26960398 SUPPORT Human Clinical
"SCLC-like (n = 18), characterized by TP53+RB1 co-mutation/loss and other SCLC-type alterations, including MYCL amplification"
Defines the SCLC-like subset by TP53+RB1 co-alteration.
PMID:29066508 SUPPORT Human Clinical
"RB1 mutation and protein loss were detected in 47% (n = 37) and 72% (n = 78) of the cases, respectively."
Gives the frequency of RB1 mutation and of Rb protein loss in a registry-based LCNEC cohort.
PMID:29535388 SUPPORT Human Clinical
"somatic alterations of RB1 and STK11/KEAP1 were detected in 82% of the cases (n = 49) and occurred in a mutually exclusive fashion"
Establishes that the RB1 and STK11/KEAP1 branches are mutually exclusive.
+ 1 more reference
STK11 and KEAP1 Biallelic Inactivation
Biallelic inactivation of STK11 (LKB1) and/or KEAP1, in the absence of RB1 co-alteration, defines the NSCLC-like (Rekhtman) or type I (George) subgroup. STK11 loss deregulates LKB1-AMPK-mTOR energy sensing and KEAP1 loss constitutively activates NRF2 antioxidant signalling. This branch frequently also carries activating KRAS mutations.
STK11 hgnc:11389 HUGO Gene Nomenclature Committee (hgnc) Relation: this pathophysiological event involves this gene This pathophysiological event involves STK11 (hgnc:11389). hgnc:11389 is a gene from the HUGO Gene Nomenclature Committee. KEAP1 hgnc:23177 HUGO Gene Nomenclature Committee (hgnc) Relation: this pathophysiological event involves this gene This pathophysiological event involves KEAP1 (hgnc:23177). hgnc:23177 is a gene from the HUGO Gene Nomenclature Committee. KRAS hgnc:6407 HUGO Gene Nomenclature Committee (hgnc) Relation: this pathophysiological event involves this gene This pathophysiological event involves KRAS (hgnc:6407). hgnc:6407 is a gene from the HUGO Gene Nomenclature Committee.
Downstream
Neuroendocrine Lineage Programme Expression The type I subgroup retains a high neuroendocrine transcriptional programme (ASCL1-high, DLL3-high, NOTCH-low). The association is transcriptomic; no causal mechanism from STK11/KEAP1 loss to lineage state has been demonstrated in LCNEC.
Show evidence (3 references)
PMID:26960398 SUPPORT Human Clinical
"NSCLC-like (n = 25), characterized by the lack of coaltered TP53+RB1 and nearly universal occurrence of NSCLC-type mutations (STK11, KRAS, and KEAP1)"
Defines the NSCLC-like subset by STK11/KRAS/KEAP1 alteration without TP53+RB1 co-alteration.
PMID:29535388 SUPPORT Human Clinical
"Combined with loss-of-heterozygosity (LOH), bi-allelic alterations of STK11 and KEAP1 were found in 37% of the cases"
Quantifies biallelic STK11/KEAP1 alteration as the defining lesion of the type I subgroup.
PMID:38159439 SUPPORT Human Clinical
"These NSCLC-like subtype-defining GAs included SMARCA4, KRAS, FGF3/4/19, STK11, CDKN2A/B, MTAP, and CCND1."
Extends the NSCLC-like lesion set beyond STK11/KEAP1/KRAS in a large clinical genomic profiling cohort.
Loss of G1/S Cell-Cycle Checkpoint Control
Combined TP53 and RB1 inactivation removes both the p53 damage checkpoint and the Rb-enforced G1/S restriction point, the canonical evading-growth-suppressors lesion. In LCNEC this is the SCLC-like branch and is accompanied by measurably higher proliferative activity than in the STK11/KEAP1 branch.
G1/S transition of mitotic cell cycle GO:0000082 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves increased G1/S transition of mitotic cell cycle (GO:0000082). GO:0000082 is a biological process from the Gene Ontology. ↑ INCREASED
Animal models
Quadruple tumour-suppressor knockout mouse (Rb1/Rbl1/Pten/Trp53) Mouse recapitulates Combined Rb1/Rbl1/Trp53 inactivation reproduces the checkpoint-loss lesion that defines the SCLC-like branch of human LCNEC.
Downstream
High-Grade Proliferative Activity and Necrosis Loss of checkpoint control produces the defining high mitotic rate.
Show evidence (1 reference)
PMID:26960398 SUPPORT Human Clinical
"higher proliferative activity in SCLC-like tumors (P < 0.0001)"
Demonstrates that the TP53+RB1 branch translates into a measurably higher proliferative rate.
Neuroendocrine Lineage Programme Expression
LCNEC expresses a neuroendocrine differentiation programme demonstrable as chromogranin A, synaptophysin and CD56 immunoreactivity, and transcriptionally as ASCL1 and DLL3 expression in the neuroendocrine-high subgroup. This programme, not the genomic lesion set, is what places LCNEC transcriptionally closest to small cell lung carcinoma and justifies its WHO classification as a neuroendocrine carcinoma rather than an NSCLC variant. DLL3 expression in this branch is the rationale for DLL3-directed therapy.
pulmonary neuroendocrine cell CL:1000223 Cell Ontology (CL) Relation: this pathophysiological event involves this cell type This pathophysiological event involves pulmonary neuroendocrine cell (CL:1000223). CL:1000223 is a cell type from the Cell Ontology.
ASCL1 hgnc:738 HUGO Gene Nomenclature Committee (hgnc) Relation: this pathophysiological event involves this gene This pathophysiological event involves ASCL1 (hgnc:738). hgnc:738 is a gene from the HUGO Gene Nomenclature Committee. DLL3 hgnc:2909 HUGO Gene Nomenclature Committee (hgnc) Relation: this pathophysiological event involves this gene This pathophysiological event involves DLL3 (hgnc:2909). hgnc:2909 is a gene from the HUGO Gene Nomenclature Committee.
neuroendocrine cell differentiation GO:0061101 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves neuroendocrine cell differentiation (GO:0061101). GO:0061101 is a biological process from the Gene Ontology.
Animal models
Quadruple tumour-suppressor knockout mouse (Rb1/Rbl1/Pten/Trp53) Mouse partially recapitulates The model reproduces the neuroendocrine carcinoma lineage and shows that restricting the same lesions to basal cells yields SCLC instead, directly demonstrating cell-of-origin control of the neuroendocrine phenotype.
Downstream
High-Grade Proliferative Activity and Necrosis The neuroendocrine programme accompanies, rather than causes, the high-grade phenotype; both are required for the diagnosis.
Show evidence (2 references)
PMID:29535388 SUPPORT Human Clinical
"instead LCNECs form distinct transcriptional subgroups with closest similarity to SCLC"
Establishes that LCNEC's transcriptional identity is neuroendocrine and SCLC-proximate.
PMID:30485478 SUPPORT Human Clinical
"positive staining for greater than or equal to two of three neuroendocrine IHC markers increased the sensitivity for LCNEC from 47% to 93% on paired biopsy specimens"
Shows that the neuroendocrine programme is demonstrable immunohistochemically and is diagnostically decisive.
NOTCH Pathway Dysregulation
Inactivating NOTCH-family mutations occur in about a quarter of NSCLC-like LCNEC, and NOTCH pathway activity is high in the type II subgroup that shows low neuroendocrine marker expression. NOTCH signalling is an established regulator of the neuroendocrine-versus-non-neuroendocrine fate switch in lung epithelium, which makes it the most plausible link between the genomic subgroups and their divergent lineage states.
Notch signaling pathway GO:0007219 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves Notch signaling pathway (GO:0007219). GO:0007219 is a biological process from the Gene Ontology.
Downstream
Neuroendocrine Lineage Programme Expression NOTCH activity is inversely associated with neuroendocrine marker expression across the LCNEC subgroups.
Show evidence (1 reference)
PMID:26960398 SUPPORT Human Clinical
"more frequent mutations in NOTCH family genes (28%), implicated as key regulators of neuroendocrine differentiation"
Quantifies NOTCH-family mutation in LCNEC and names its role in neuroendocrine differentiation.
High-Grade Proliferative Activity and Necrosis
A mitotic rate above 10 mitoses per 2 square millimetres together with extensive, often geographic necrosis is a defining diagnostic criterion of LCNEC and separates it from the low-grade (typical carcinoid) and intermediate-grade (atypical carcinoid) neuroendocrine tumours.
cell population proliferation GO:0008283 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves increased cell population proliferation (GO:0008283). GO:0008283 is a biological process from the Gene Ontology. ↑ INCREASED
Downstream
Local Tumour Growth with Central or Peripheral Presentation Unrestrained proliferation produces the expanding primary mass.
Early Metastatic Dissemination The high-grade phenotype underlies the characteristic early and widespread dissemination.
Show evidence (1 reference)
PMID:28572122 SUPPORT Human Clinical
"a subtype of lung cancer with neuroendocrine morphology, neuroendocrine differentiation on immunohistochemistry, a high mitotic rate"
States the defining combination of neuroendocrine features with a high mitotic rate.
Local Tumour Growth with Central or Peripheral Presentation
The primary tumour grows as either a peripheral mass, which is the majority pattern, or a central tumour invading the segmental or lobar bronchus. The distinction is prognostically and biologically real: central tumours are more strongly associated with smoking, present at higher stage and larger size, and carry markedly worse survival, while peripheral tumours more often retain Rb protein and harbour EGFR mutations.
bronchial epithelial cell CL:0002328 Cell Ontology (CL) Relation: this pathophysiological event involves this cell type This pathophysiological event involves bronchial epithelial cell (CL:0002328). CL:0002328 is a cell type from the Cell Ontology.
Downstream
Lung Neoplasm The expanding primary constitutes the clinically detected lung neoplasm.
Show evidence (2 references)
PMID:29413048 SUPPORT Human Clinical
"The tumors with invasion of the segmental and/or lobar bronchus were classified as central LCNEC and those without as peripheral LCNEC."
Defines the central versus peripheral growth patterns by bronchial invasion.
PMID:29413048 SUPPORT Human Clinical
"The majority of LCNEC proved to be of the peripheral type (64.3%, 81/126). Central tumors were associated with smoking habit (p = 0.047), higher TNM-stage (p = 0.014) and larger tumor size (p < 0.001)."
Quantifies the peripheral predominance and the clinical correlates of central growth.
Early Metastatic Dissemination
LCNEC disseminates early and widely. In population data the majority of patients present at stage IV, and brain metastasis is more frequent than in either small cell or non-small cell lung cancer, making the central nervous system a characteristic site of colonisation.
Downstream
Brain Metastasis Colonisation of the central nervous system produces the brain metastases that are disproportionately frequent in LCNEC.
Show evidence (2 references)
PMID:31601526 SUPPORT Human Clinical
"LCNEC was more common among male subjects, and disease usually presented at stage IV (55%)"
Establishes that most patients present with disseminated disease.
PMID:31601526 SUPPORT Human Clinical
"Brain metastasis occurred more frequently in LCNEC (19.2%) than SCLC (16.7%, P < .001) or NSCLC (13%, P < .001)"
Documents the disproportionate brain tropism of LCNEC.
✶

Histopathology

1
Neuroendocrine Morphology with High Mitotic Rate and Necrosis
Organoid nesting, palisading and rosette-like structures with large cells, abundant cytoplasm and prominent nucleoli, combined with a mitotic rate above 10 per 2 square millimetres and extensive necrosis. Neuroendocrine morphology is frequently not appreciable on small biopsies, which is the main reason LCNEC is underdiagnosed pre-operatively.
Show evidence (2 references)
PMID:30485478 SUPPORT Human Clinical
"Neuroendocrine morphology was absent in 53% (n = 17 of 32) of paired biopsy specimens"
Quantifies how often the defining morphology is missing on biopsy material.
PMID:30485478 SUPPORT Human Clinical
"LCNEC is difficult to diagnose because neuroendocrine morphology is frequently absent in biopsy specimens."
States the diagnostic consequence of the morphology being biopsy-dependent.
⬡

Pathograph

Use the checkboxes to hide or show graph categories. Hover nodes for evidence and cross-linked metadata.
Pathograph: causal mechanism network for Large Cell Neuroendocrine Carcinoma Interactive directed graph showing how pathophysiology mechanisms, phenotypes, genetic factors and variants, experimental models, environmental triggers, and treatments relate through causal and linked edges.
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Phenotypes

2
Neoplasm 1
Lung Neoplasm VERY_FREQUENT Neoplasm of the lung HP:0100526 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Neoplasm of the lung (HP:0100526). HP:0100526 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:31601526 SUPPORT Human Clinical
"Large-cell neuroendocrine carcinoma (LCNEC) accounts for approximately 3% of lung malignancies."
Establishes LCNEC as a lung malignancy in the dominant pulmonary form.
Other 1
Brain Metastasis OCCASIONAL Brain neoplasm HP:0030692 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Brain neoplasm (HP:0030692). HP:0030692 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:31601526 SUPPORT Human Clinical
"Brain metastasis occurred more frequently in LCNEC (19.2%) than SCLC (16.7%, P < .001) or NSCLC (13%, P < .001)"
Reports brain metastasis in 19.2% of LCNEC, which maps to the OCCASIONAL band (5-29%).
🧬

Genetic Associations

5
TP53
Gene: TP53 hgnc:11998 HUGO Gene Nomenclature Committee (hgnc) Relation: this disease-associated gene is this gene This disease-associated gene is TP53 (hgnc:11998). hgnc:11998 is a gene from the HUGO Gene Nomenclature Committee. relationship_type: SOMATIC_DRIVER variant_origin: SOMATIC
Show evidence (1 reference)
PMID:29535388 SUPPORT Human Clinical
"TP53 was the most frequently mutated gene (92%)"
Establishes TP53 as the most frequently altered gene in LCNEC.
RB1
Gene: RB1 hgnc:9884 HUGO Gene Nomenclature Committee (hgnc) Relation: this disease-associated gene is this gene This disease-associated gene is RB1 (hgnc:9884). hgnc:9884 is a gene from the HUGO Gene Nomenclature Committee. relationship_type: SOMATIC_DRIVER variant_origin: SOMATIC
Show evidence (1 reference)
PMID:29066508 SUPPORT Human Clinical
"RB1 mutation and protein loss were detected in 47% (n = 37) and 72% (n = 78) of the cases, respectively."
Gives RB1 mutation and protein-loss frequencies in a national registry cohort.
STK11
Gene: STK11 hgnc:11389 HUGO Gene Nomenclature Committee (hgnc) Relation: this disease-associated gene is this gene This disease-associated gene is STK11 (hgnc:11389). hgnc:11389 is a gene from the HUGO Gene Nomenclature Committee. relationship_type: SOMATIC_DRIVER variant_origin: SOMATIC
Show evidence (1 reference)
PMID:26960398 SUPPORT Human Clinical
"Commonly altered genes in LCNEC included TP53 (78%), RB1 (38%), STK11 (33%), KEAP1 (31%), and KRAS (22%)"
Reports STK11 alteration in 33% of LCNEC.
KEAP1
Gene: KEAP1 hgnc:23177 HUGO Gene Nomenclature Committee (hgnc) Relation: this disease-associated gene is this gene This disease-associated gene is KEAP1 (hgnc:23177). hgnc:23177 is a gene from the HUGO Gene Nomenclature Committee. relationship_type: SOMATIC_DRIVER variant_origin: SOMATIC
Show evidence (1 reference)
PMID:26960398 SUPPORT Human Clinical
"Commonly altered genes in LCNEC included TP53 (78%), RB1 (38%), STK11 (33%), KEAP1 (31%), and KRAS (22%)"
Reports KEAP1 alteration in 31% of LCNEC.
KRAS
Gene: KRAS hgnc:6407 HUGO Gene Nomenclature Committee (hgnc) Relation: this disease-associated gene is this gene This disease-associated gene is KRAS (hgnc:6407). hgnc:6407 is a gene from the HUGO Gene Nomenclature Committee. relationship_type: SOMATIC_DRIVER variant_origin: SOMATIC
Show evidence (1 reference)
PMID:26960398 SUPPORT Human Clinical
"Commonly altered genes in LCNEC included TP53 (78%), RB1 (38%), STK11 (33%), KEAP1 (31%), and KRAS (22%)"
Reports KRAS mutation in 22% of LCNEC, within the NSCLC-like branch.
💊

Medical Actions

5
Platinum-Etoposide Chemotherapy
Action: chemotherapyNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is chemotherapy (NCIT:C15632). NCIT:C15632 is a clinical intervention from the NCI Thesaurus. Ontology label: Chemotherapy NCIT:C15632
Agent: cisplatin CHEBI:27899 Chemical Entities of Biological Interest (CHEBI) Relation: this treatment uses this therapeutic agent This treatment uses cisplatin (CHEBI:27899). CHEBI:27899 is a therapeutic agent from Chemical Entities of Biological Interest. carboplatin CHEBI:31355 Chemical Entities of Biological Interest (CHEBI) Relation: this treatment uses this therapeutic agent This treatment uses carboplatin (CHEBI:31355). CHEBI:31355 is a therapeutic agent from Chemical Entities of Biological Interest. etoposide CHEBI:4911 Chemical Entities of Biological Interest (CHEBI) Relation: this treatment uses this therapeutic agent This treatment uses etoposide (CHEBI:4911). CHEBI:4911 is a therapeutic agent from Chemical Entities of Biological Interest.
Small cell lung cancer-type chemotherapy, historically the default first-line regimen for advanced LCNEC by extrapolation from SCLC. Note that its superiority is not established, and in RB1 wild-type tumours it performs worse than NSCLC-type chemotherapy.
Mechanism Target:
INHIBITS High-Grade Proliferative Activity and Necrosis — Cytotoxic chemotherapy targets the rapidly proliferating compartment that defines the high-grade phenotype.
Show evidence (1 reference)
PMID:34513663 SUPPORT Human Clinical
"the historical regimen of platinum based therapy in combination with etoposide or irinotecan remains among the commonly used first line therapies"
Establishes platinum-etoposide as a standard first-line cytotoxic regimen in advanced LCNEC.
Show evidence (1 reference)
PMID:34513663 SUPPORT Human Clinical
"In advanced disease, the historical regimen of platinum based therapy in combination with etoposide or irinotecan remains among the commonly used first line therapies"
Documents the standard-of-care status of platinum-etoposide in advanced LCNEC.
NSCLC-Type Platinum Doublet Chemotherapy
Action: chemotherapyNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is chemotherapy (NCIT:C15632). NCIT:C15632 is a clinical intervention from the NCI Thesaurus. Ontology label: Chemotherapy NCIT:C15632
Agent: gemcitabine CHEBI:175901 Chemical Entities of Biological Interest (CHEBI) Relation: this treatment uses this therapeutic agent This treatment uses gemcitabine (CHEBI:175901). CHEBI:175901 is a therapeutic agent from Chemical Entities of Biological Interest. paclitaxel CHEBI:45863 Chemical Entities of Biological Interest (CHEBI) Relation: this treatment uses this therapeutic agent This treatment uses paclitaxel (CHEBI:45863). CHEBI:45863 is a therapeutic agent from Chemical Entities of Biological Interest.
Platinum combined with gemcitabine or a taxane. In a national registry cohort this produced longer overall survival than either pemetrexed-based or etoposide-based treatment, and in RB1 wild-type tumours it significantly outperformed platinum-etoposide. This is the clearest example in LCNEC of molecular subtype guiding chemotherapy choice.
Mechanism Target:
INHIBITS High-Grade Proliferative Activity and Necrosis — Cytotoxic chemotherapy targets the proliferating tumour compartment. RB1 status does not change the drug target but predicts which cytotoxic strategy performs better.
Show evidence (1 reference)
PMID:29066508 SUPPORT Human Clinical
"Patients with LCNEC tumors that carry a wild-type RB1 gene or express the RB1 protein do better with NSCLC-GEM/TAX treatment than with SCLC-PE chemotherapy."
Establishes RB1 status as predictive of differential benefit between the two chemotherapy strategies.
Show evidence (2 references)
PMID:29066508 SUPPORT Human Clinical
"Patients with RB1 wild-type LCNEC treated with NSCLC-GEM/TAX had a significantly longer OS [9.6; 95% confidence interval (CI), 7.7-11.6 months] than those treated with SCLC-PE [5.8 (5.5-6.1); P = 0.026]"
Gives the survival difference by RB1 status between NSCLC-type and SCLC-type chemotherapy.
PMID:28572122 SUPPORT Human Clinical
"In patients with LCNEC, NSCLC-t chemotherapy results in longer overall survival compared to NSCLC-pt and SCLC-t chemotherapy."
Independent registry evidence that NSCLC-type chemotherapy gives the longest overall survival.
Dual Immune Checkpoint Blockade
Action: PharmacotherapyNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is Pharmacotherapy (NCIT:C15986). NCIT:C15986 is a clinical intervention from the NCI Thesaurus. NCIT:C15986
Agent: ipilimumab NCIT:C2654 NCI Thesaurus (NCIT) Relation: this treatment uses this therapeutic agent This treatment uses ipilimumab (NCIT:C2654). NCIT:C2654 is a therapeutic agent from the NCI Thesaurus. nivolumab NCIT:C68814 NCI Thesaurus (NCIT) Relation: this treatment uses this therapeutic agent This treatment uses nivolumab (NCIT:C68814). NCIT:C68814 is a therapeutic agent from the NCI Thesaurus.
Ipilimumab plus nivolumab, studied prospectively in the high-grade neuroendocrine neoplasm cohort of the DART SWOG S1609 basket trial. Activity is real but modest, and the cohort was histologically and anatomically mixed rather than LCNEC-specific.
Show evidence (1 reference)
PMID:33882143 SUPPORT Human Clinical
"Ipilimumab plus nivolumab demonstrated a 26% ORR in patients with high-grade neuroendocrine neoplasms, with durable responses seen in patients with refractory disease."
Reports prospective activity of dual checkpoint blockade in high-grade neuroendocrine neoplasms. Curated as PARTIAL because the 19-patient cohort was not LCNEC-specific.
Surgical Resection
Action: Surgical ProcedureNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is Surgical Procedure (NCIT:C15329). NCIT:C15329 is a clinical intervention from the NCI Thesaurus. NCIT:C15329
Complete resection is the treatment of choice for early-stage, resectable LCNEC, consistent with the observation that stage I-III LCNEC behaves like non-small cell lung cancer.
Show evidence (1 reference)
PMID:31601526 SUPPORT Human Clinical
"Stage I-III LCNEC behaves similarly to NSCLC, whereas stage IV is more akin to SCLC."
Supports an NSCLC-like, resection-oriented approach at stages I-III. PARTIAL because this population study reports behaviour rather than directly comparing surgical against non-surgical management.
Site-Adapted Chemotherapy for Extrapulmonary LCNEC
Action: chemotherapyNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is chemotherapy (NCIT:C15632). NCIT:C15632 is a clinical intervention from the NCI Thesaurus. Ontology label: Chemotherapy NCIT:C15632
For extrathoracic primaries, gastrointestinal-type regimens are used in addition to the platinum backbone, reflecting the site rather than the pulmonary paradigm.
Show evidence (1 reference)
PMID:34513663 SUPPORT Human Clinical
"however for extra thoracic LCNEC regimens like FOLFOX, FOLFOIRI and CAPTEM can also be used"
Documents the site-adapted chemotherapy options for extrapulmonary LCNEC.
🌍

Environmental Factors

1
Tobacco smoking
Left without an `exposure_term` binding pending an ECTO lookup for a tobacco-smoke exposure class; the mechanism link is what places this exposure in the pathograph.
Heavy tobacco smoking is the dominant environmental risk factor for pulmonary LCNEC. Sequencing confirms a dominant tobacco mutational signature in these tumours.
Show evidence (1 reference)
PMID:29535388 SUPPORT Human Clinical
"which confirmed a prominent smoking-related signature (signature 4"
Confirms the tobacco mutational signature as the dominant mutational process in LCNEC.
Mechanism Target:
TRIGGERS Tobacco Carcinogen Exposure and Smoking-Associated Mutagenesis — Chronic smoking is the exposure that generates the carcinogen-driven mutational process initiating LCNEC.
Show evidence (1 reference)
PMID:29535388 SUPPORT Human Clinical
"LCNEC and SCLC are clinically aggressive tumors presenting in elderly heavy-smokers"
Establishes heavy smoking as the population context in which LCNEC arises.
🔬

Diagnosis

1
Combined morphologic and immunohistochemical diagnosis
Diagnosis requires neuroendocrine morphology, a high mitotic rate and neuroendocrine differentiation confirmed by immunohistochemistry (CD56, chromogranin A, synaptophysin). Because neuroendocrine morphology is often absent on small biopsies, positivity for at least two of three neuroendocrine markers substantially improves sensitivity and is the practical diagnostic rule on biopsy material.
Show evidence (2 references)
PMID:30485478 SUPPORT Human Clinical
"In NSCLC devoid of obvious morphological squamous or adenocarcinoma features, positive staining in greater than or equal to two of three neuroendocrine IHC stains supports the diagnosis of LCNEC."
States the operational immunohistochemical diagnostic rule for biopsy specimens.
PMID:30485478 SUPPORT Human Clinical
"further validated using an independent TMA of LCNEC and NSCLC with sensitivity and specificity of 80% and 99%, respectively"
Gives the validated performance of the two-of-three marker rule.
📈

Progression

1
Stage-dependent divergent clinical behaviour
An unusual and clinically important feature of LCNEC is that its natural history tracks non-small cell lung cancer at stages I-III but small cell lung cancer at stage IV. Overall survival is poor, with five-year survival below 15-25% in genomically characterised cohorts.
Show evidence (2 references)
PMID:31601526 SUPPORT Human Clinical
"Survival in patients with stage I-III LCNEC mirrored survival trends of patients with NSCLC, whereas stage IV LCNEC behaved similarly to SCLC."
States the stage-dependent divergence in clinical behaviour.
PMID:29535388 SUPPORT Human Clinical
"with 5-year survival rates below 15–25% (LCNEC) and 5% (SCLC), respectively"
Gives the five-year survival range for LCNEC.
📊

Prevalence

2
United States (SEER 2010-2015, lung primaries)
Point Prevalence Rare
LCNEC accounted for 1681 of 195,148 lung cancer cases (0.9%) in SEER 2010-2015. Other series place it at approximately 3% of lung malignancies; the difference reflects registry coding versus panel-reviewed pathology, and LCNEC is known to be underdiagnosed on biopsy. Recorded as a proportion of lung cancers, not as a population rate, because the sources report it that way.
Show evidence (1 reference)
PMID:31601526 SUPPORT Human Clinical
"A total of 195,148 cases of lung cancer, including 1681 (0.9%) cases of LCNEC, were analyzed."
Gives the registry-based share of lung cancers diagnosed as LCNEC.
Resected lung cancers (European genomic cohort)
Point Prevalence Rare
LCNEC as a proportion of resected lung cancers.
Show evidence (1 reference)
PMID:29535388 SUPPORT Human Clinical
"LCNECs account for 2–3% of all resected lung cancers"
Independent estimate of LCNEC frequency among resected lung cancers.
🌍

Epidemiology

3
Rising incidence and mortality
The recorded incidence of LCNEC has been rising, driven mainly by stage IV disease, and annual mortality doubled over the period studied in SEER. Part of this trend may reflect improving pathological recognition rather than changing biology; see the under-diagnosis knowledge gap.
Show evidence (1 reference)
PMID:31601526 SUPPORT Human Clinical
"Incidence increased by 0.011 people per 100,000 per year, primarily of stage IV disease. Annual mortality from LCNEC doubled over the time period studied."
Documents the rising incidence and mortality of LCNEC.
Marked male predominance and later-middle-age onset
A single-centre surgical series of 62 patients was 95% male with a mean age of 60.3 years, an extreme sex skew consistent with the historical distribution of heavy smoking. Registry data show the same direction of effect more moderately, so the 95% figure should be read as a single-centre observation rather than a population estimate.
Show evidence (1 reference)
PMID:32584230 SUPPORT Human Clinical
"The patients were predominantly (95%) men (male:female=59:3) with their average age being 60.3±8.6 years."
Gives the sex ratio and mean age at diagnosis in a surgical LCNEC series.
Survival by central versus peripheral tumour location
Tumour location is a strong independent prognostic factor, with peripheral tumours surviving markedly longer than central ones.
Show evidence (1 reference)
PMID:29413048 SUPPORT Human Clinical
"Peripheral tumors had better survival compared with central tumors (median OS: 4.04 vs. 1.51 years, p < 0.001)."
Quantifies the survival difference between central and peripheral LCNEC.
🔀

Differential Diagnoses

2

Conditions with similar clinical presentations that must be differentiated from Large Cell Neuroendocrine Carcinoma:

Small cell lung carcinoma MONDO:0008433
Overlapping Features The principal differential. SCLC shares neuroendocrine differentiation and the TP53+RB1 genotype but differs in cytology (small cells, scant cytoplasm, nuclear moulding, inconspicuous nucleoli). Transcriptionally LCNEC sits closest to SCLC, which is why the distinction rests on cytomorphology rather than on marker expression.
Show evidence (1 reference)
PMID:29535388 SUPPORT Human Clinical
"instead LCNECs form distinct transcriptional subgroups with closest similarity to SCLC"
Establishes the transcriptional proximity that makes SCLC the key differential.
Atypical carcinoid
Overlapping Features The intermediate-grade neuroendocrine tumour. Shares neuroendocrine morphology and marker expression but is separated from LCNEC by mitotic rate and necrosis; a small minority of LCNEC-diagnosed tumours are genomically carcinoid-like, which is a recognised classification boundary problem.
Show evidence (1 reference)
PMID:26960398 SUPPORT Human Clinical
"and carcinoid-like (n = 2), characterized by MEN1 mutations and low mutation burden"
Documents the genomically carcinoid-like minority within histologically diagnosed LCNEC.
🐁

Animal Models

1
Quadruple tumour-suppressor knockout mouse (Rb1/Rbl1/Pten/Trp53)
The first defined mouse model of LCNEC. In an Rbl1-null background, deletion of Rb1, Pten and Trp53 by broadly targeted Ad-CMVcre produces LCNEC, whereas the identical genetic lesion delivered to basal cells by Ad-K5cre produces small cell lung carcinoma instead. This makes cell of origin, not genotype, the determinant of which high-grade neuroendocrine carcinoma develops.
Species
Mouse
Genotype
Rbl1-null; Rb1, Pten and Trp53 conditional alleles deleted by adenoviral Cre
Publication
PMID:31611390
Pathograph links
Loss of G1/S Cell-Cycle Checkpoint Control recapitulates fidelity: moderate Combined Rb1/Rbl1/Trp53 inactivation reproduces the checkpoint-loss lesion that defines the SCLC-like branch of human LCNEC.
Limitations: The model adds Rbl1 (p130) and Pten inactivation, which are not established recurrent drivers of human LCNEC, so the genotype is broader than the human lesion set. The tumours are also induced synchronously in immunocompetent mice rather than arising through decades of carcinogen exposure.
Show evidence (2 references)
PMID:31611390 SUPPORT Model Organism
"In an Rbl1-null background, deletion of Rb1, Pten, and Trp53 floxed alleles after Ad-CMVcre infection in a wide variety of lung epithelial cells produces LCNEC."
Establishes that this genotype and delivery route generate LCNEC in mice.
+ 1 more reference
Neuroendocrine Lineage Programme Expression partially recapitulates fidelity: moderate The model reproduces the neuroendocrine carcinoma lineage and shows that restricting the same lesions to basal cells yields SCLC instead, directly demonstrating cell-of-origin control of the neuroendocrine phenotype.
Limitations: The experiment establishes that cell of origin determines which tumour type arises, but it does not model the ASCL1/DLL3/NOTCH transcriptional subgrouping that distinguishes human type I from type II LCNEC.
Show evidence (1 reference)
PMID:31611390 SUPPORT Model Organism
"Meanwhile, inactivation of these genes using Ad-K5cre in basal cells leads to the development of SCLC, thus differentially influencing the lung cancer type developed."
Demonstrates cell-of-origin control over the resulting neuroendocrine carcinoma type.
Show evidence (1 reference)
PMID:31611390 SUPPORT Model Organism
"So far, a defined model of LCNEC has not been reported."
Establishes this as the first defined animal model of LCNEC.
{ }

Source YAML

click to show 
name: Large Cell Neuroendocrine Carcinoma
creation_date: "2026-08-19T21:10:00Z"
description: >-
  Large cell neuroendocrine carcinoma (LCNEC) is a rare, high-grade, poorly
  differentiated neuroendocrine carcinoma composed of large malignant epithelial
  cells that combine neuroendocrine morphology (organoid nesting, palisading,
  rosettes) with immunohistochemically demonstrable neuroendocrine
  differentiation, a high mitotic rate and extensive necrosis. The lung is the
  prototype and best-studied site, where LCNEC accounts for roughly 1-3% of lung
  cancers and arises almost exclusively in older heavy smokers, but the entity is
  also recognised at many extrapulmonary sites. Genomically LCNEC is not one
  disease: near-universal TP53 inactivation is followed by a bifurcation into a
  TP53+RB1 co-altered (SCLC-like, or type II) group and a STK11/KEAP1-altered
  (NSCLC-like, or type I) group, which are largely mutually exclusive and which
  differ in neuroendocrine transcriptional programme and in chemotherapy
  outcome. Clinically LCNEC behaves like non-small cell lung cancer at stages
  I-III and like small cell lung cancer at stage IV, and prognosis is poor.
category: Neoplastic
categories:
- Solid Tumor
- Neuroendocrine Neoplasm
- Thoracic Malignancy
parents:
- Neuroendocrine Carcinoma
synonyms:
- LCNEC
- large cell NEC
- large-cell neuroendocrine carcinoma
- high-grade neuroendocrine carcinoma, large cell type
disease_term:
  preferred_term: large cell neuroendocrine carcinoma
  term:
    id: MONDO:0005057
    label: large cell neuroendocrine carcinoma
notes: >-
  Scope. This entry is the site-agnostic LCNEC entity (MONDO:0005057), whose
  MONDO children are the organ-specific LCNECs modelled here under
  `has_subtypes`. Because the overwhelming majority of the mechanistic and
  clinical literature concerns the pulmonary form, the pathograph and the
  treatment/prevalence sections are pulmonary-anchored and say so; extrapulmonary
  LCNEC is captured as subtypes plus a site-specific treatment entry rather than
  by silently generalising lung data. Thymic LCNEC (MONDO:0003047) is already
  curated in depth as a `has_subtypes` facet of
  `kb/disorders/Thymic_Neuroendocrine_Carcinoma.yaml`; it is listed here as a
  subtype for completeness and deliberately not re-derived.

  Deep research. `just research-disorder falcon` was attempted first (the repo
  default) and failed with HTTP 402 Payment Required from the Edison API, so no
  falcon report exists for this entry. Two providers did complete and both
  reports are committed: `claude_code` (35/35 references resolved, confabulation
  rate 0.0, 0 off topic) and `openscientist` (49/49 resolved, 7/7 quoted claims
  found in source, 0 off topic). NEC preflight against MONDO:0005057 returned
  SKIP for both, because MONDO records no causal gene for a sporadic carcinoma;
  the manual fallback was therefore run - the reports' top-mentioned genes are
  the expected TP53/RB1/STK11/KEAP1/ASCL1 set, MONDO:0005057 carries no OMIM
  xref to contradict, and the flagged acronym "LCNEC" names no other MONDO
  entity.

  Despite validating cleanly, the claude_code report proposed three incorrect
  ontology identifiers, which were caught and not used: KEAP1 as HGNC:6396
  (correct: hgnc:23177), pulmonary neuroendocrine cell as CL:0002251 (correct:
  CL:1000223), and the disease itself as a MONDO:0018316-class term (correct:
  MONDO:0005057). Every identifier in this entry was independently re-resolved
  with OAK. Reference validation checks that a citation resolves, not that an
  ontology term is real - this is the standard treat-DR-as-leads discipline, not
  an incidental problem with one report.

  Phenotypes deliberately not curated. Cough, haemoptysis, dyspnoea and
  constitutional weight loss are the typical presenting features of LCNEC as of
  any thoracic malignancy, and earlier drafts of this entry carried them. They
  were removed because none of the sources available here actually documents or
  quantifies them in LCNEC specifically - the only snippets that could be
  attached were general statements about LCNEC being aggressive, which do not
  support a symptom claim. They are recorded in prose here instead of being
  given evidence items that do not say what they are cited for. The curated
  phenotypes are limited to the two that are directly evidenced (the lung
  primary, and brain metastasis at 19.2%); a clinical series that quantifies
  presenting symptoms would be the right basis for adding the rest.

  Type I / type II naming. The two large genomic studies use opposite-sounding
  labels for overlapping groups and this entry preserves both rather than
  flattening them: Rekhtman's SCLC-like group (TP53+RB1 co-altered) corresponds
  to George's type II, and Rekhtman's NSCLC-like group (STK11/KRAS/KEAP1)
  corresponds to George's type I. Counterintuitively it is George's type I, the
  group named for NSCLC-type genomic lesions, that carries the higher
  neuroendocrine transcriptional programme (ASCL1high/DLL3high/NOTCHlow), while
  type II shows reduced neuroendocrine markers. Curators should not correct this
  apparent inversion; it is what the sources report.
references:
- reference: PMID:26960398
  title: "Next-Generation Sequencing of Pulmonary Large Cell Neuroendocrine Carcinoma Reveals Small Cell Carcinoma-like and Non-Small Cell Carcinoma-like Subsets."
- reference: PMID:29535388
  title: "Integrative genomic profiling of large-cell neuroendocrine carcinomas reveals distinct subtypes of high-grade neuroendocrine lung tumors."
mappings:
  mondo_mappings:
  - mapping_predicate: skos:exactMatch
    term:
      id: MONDO:0005057
      label: large cell neuroendocrine carcinoma
has_subtypes:
- name: Pulmonary LCNEC
  display_name: Pulmonary large cell neuroendocrine carcinoma
  description: >-
    LCNEC arising in the lung. The prototype and by far the best-characterised
    form; essentially all of the genomic subtyping and chemotherapy-outcome
    literature curated in this entry derives from pulmonary cohorts.
  subtype_term:
    preferred_term: pulmonary large cell neuroendocrine carcinoma
    term:
      id: MONDO:0003960
      label: pulmonary large cell neuroendocrine carcinoma
  evidence:
  - reference: PMID:29535388
    reference_title: "Integrative genomic profiling of large-cell neuroendocrine carcinomas reveals distinct subtypes of high-grade neuroendocrine lung tumors."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "LCNECs account for 2–3% of all resected lung cancers and belong to the category of neuroendocrine lung tumors"
    explanation: Establishes the pulmonary form as a defined entity within neuroendocrine lung tumours.
- name: Combined Pulmonary LCNEC
  display_name: Lung combined large cell neuroendocrine carcinoma
  description: >-
    Pulmonary LCNEC admixed with a non-neuroendocrine component (adenocarcinoma
    or squamous cell carcinoma) or with small cell carcinoma. Notably the RB1
    alterations of the LCNEC component are frequently shared with the combined
    component, arguing for a common clonal origin rather than collision tumours.
  subtype_term:
    preferred_term: lung combined large cell neuroendocrine carcinoma
    term:
      id: MONDO:0004142
      label: lung combined large cell neuroendocrine carcinoma
  evidence:
  - reference: PMID:29535388
    reference_title: "Integrative genomic profiling of large-cell neuroendocrine carcinomas reveals distinct subtypes of high-grade neuroendocrine lung tumors."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Nineteen of 75 LCNECs included in this study showed additional histological components of lung adenocarcinoma (ADC) (n = 2), squamous cell carcinoma (SqCC) (n = 5) or SCLC (n = 12)"
    explanation: Quantifies the combined histology subtype within a genomically characterised LCNEC cohort.
- name: Thymic LCNEC
  display_name: Thymic large cell neuroendocrine carcinoma
  description: >-
    LCNEC arising in the thymus, the highest-grade member of the thymic
    neuroendocrine tumour family. Curated in depth in
    `kb/disorders/Thymic_Neuroendocrine_Carcinoma.yaml`; listed here only to make
    the site spectrum complete.
  subtype_term:
    preferred_term: thymic large cell neuroendocrine carcinoma
    term:
      id: MONDO:0003047
      label: thymic large cell neuroendocrine carcinoma
- name: Cervical LCNEC
  display_name: Cervical large cell neuroendocrine carcinoma
  description: >-
    LCNEC arising in the uterine cervix, one of the recognised gynaecological
    high-grade neuroendocrine carcinomas. Unlike the smoking-driven pulmonary
    form, cervical LCNEC is associated with high-risk HPV. A reported
    HPV18-positive case also showed a very low tumour mutational burden
    (1.21/Mb), the opposite of the high TMB that characterises pulmonary LCNEC -
    a concrete reason not to generalise the pulmonary mechanism or the pulmonary
    immunotherapy rationale across sites. That is a single case, so it is
    recorded here as a caution rather than an established site difference.
  subtype_term:
    preferred_term: cervical large cell neuroendocrine carcinoma
    term:
      id: MONDO:0006138
      label: cervical large cell neuroendocrine carcinoma
  evidence:
  - reference: PMID:42521492
    reference_title: "HPV18-Positive Cervical Large Cell Neuroendocrine Carcinoma With Rapid Progression Despite Pembrolizumab Combined With Chemotherapy: A Case Report With Immunogenomic Insights."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Biopsy showed chromogranin A and synaptophysin positivity, diffuse p16, and Ki-67%~80%."
    explanation: >-
      Documents an HPV18-positive cervical LCNEC with the defining
      neuroendocrine marker profile and high proliferation index. Curated as
      PARTIAL because this is a single case report.
- name: Pancreatic LCNEC
  display_name: Pancreatic large cell neuroendocrine carcinoma
  description: >-
    LCNEC arising in the pancreas, within the poorly differentiated pancreatic
    neuroendocrine carcinoma group.
  subtype_term:
    preferred_term: pancreatic large cell neuroendocrine carcinoma
    term:
      id: MONDO:0006347
      label: pancreatic large cell neuroendocrine carcinoma
- name: Breast LCNEC
  display_name: Breast large cell neuroendocrine carcinoma
  description: >-
    LCNEC arising in the breast, a rare high-grade neuroendocrine breast
    carcinoma.
  subtype_term:
    preferred_term: breast large cell neuroendocrine carcinoma
    term:
      id: MONDO:0003959
      label: breast large cell neuroendocrine carcinoma
pathophysiology:
- name: Tobacco Carcinogen Exposure and Smoking-Associated Mutagenesis
  biological_scale: MOLECULAR
  role: trigger
  description: >-
    Pulmonary LCNEC arises almost exclusively in older heavy smokers. Whole-exome
    and whole-genome sequencing shows a high exonic mutation rate dominated by
    C:G>A:T transversions and by COSMIC mutational signature 4, the canonical
    tobacco-carcinogen signature. This mutagenic burden is what generates the
    tumour-suppressor loss-of-function events that define both molecular
    subgroups.
  evidence:
  - reference: PMID:29535388
    reference_title: "Integrative genomic profiling of large-cell neuroendocrine carcinomas reveals distinct subtypes of high-grade neuroendocrine lung tumors."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "On average, LCNECs exhibited an exonic mutation rate of 8.6 non-synonymous mutations per million base pairs and a C:G > A:T transversion rate of 38.7%"
    explanation: Quantifies the tobacco-type mutational burden in a genomically profiled LCNEC cohort.
  - reference: PMID:29535388
    reference_title: "Integrative genomic profiling of large-cell neuroendocrine carcinomas reveals distinct subtypes of high-grade neuroendocrine lung tumors."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "LCNEC and SCLC are clinically aggressive tumors presenting in elderly heavy-smokers"
    explanation: Establishes heavy smoking as the near-universal clinical context of LCNEC.
  downstream:
  - target: TP53 Inactivation
    causal_link_type: DIRECT
    description: >-
      Carcinogen-induced mutagenesis produces the near-universal TP53
      loss-of-function events that initiate the LCNEC pathograph.
    evidence:
    - reference: PMID:29535388
      reference_title: "Integrative genomic profiling of large-cell neuroendocrine carcinomas reveals distinct subtypes of high-grade neuroendocrine lung tumors."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "TP53 was the most frequently mutated gene (92%)"
      explanation: Places TP53 loss as the dominant somatic event downstream of the smoking-driven mutational process.
- name: TP53 Inactivation
  biological_scale: MOLECULAR
  role: central_effector
  description: >-
    Biallelic TP53 loss of function is the near-universal first hit in LCNEC,
    reported in 78% of tumours by targeted sequencing and 92% by whole-exome
    sequencing. Loss of p53 abrogates DNA-damage checkpoint control and
    apoptosis, licensing both the genomic instability and the second-hit
    bifurcation that follow.
  genes:
  - preferred_term: TP53
    term:
      id: hgnc:11998
      label: TP53
  evidence:
  - reference: PMID:26960398
    reference_title: "Next-Generation Sequencing of Pulmonary Large Cell Neuroendocrine Carcinoma Reveals Small Cell Carcinoma-like and Non-Small Cell Carcinoma-like Subsets."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Commonly altered genes in LCNEC included TP53 (78%), RB1 (38%), STK11 (33%), KEAP1 (31%), and KRAS (22%)"
    explanation: Gives the mutation frequency of TP53 and of the genes defining the downstream branches.
  - reference: PMID:29535388
    reference_title: "Integrative genomic profiling of large-cell neuroendocrine carcinomas reveals distinct subtypes of high-grade neuroendocrine lung tumors."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "TP53 was the most frequently mutated gene (92%)"
    explanation: Independent whole-exome confirmation that TP53 loss is near universal.
  downstream:
  - target: Mutator Phenotype and Chromosomal Instability
    causal_link_type: DIRECT
    description: Loss of p53-dependent damage surveillance permits accumulation of mutations and copy-number change.
  - target: RB1 Biallelic Inactivation
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    description: >-
      TP53 loss is co-selected with RB1 loss in the SCLC-like/type II branch;
      the two are reported as co-mutated rather than sequentially causal.
    evidence:
    - reference: PMID:29535388
      reference_title: "Integrative genomic profiling of large-cell neuroendocrine carcinomas reveals distinct subtypes of high-grade neuroendocrine lung tumors."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "type II LCNECs bear TP53 and RB1 alterations"
      explanation: Establishes TP53 and RB1 as the co-occurring pair defining this branch.
  - target: STK11 and KEAP1 Biallelic Inactivation
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    description: >-
      In the alternative branch TP53 loss is accompanied by STK11 and/or KEAP1
      inactivation rather than by RB1 loss.
    evidence:
    - reference: PMID:29535388
      reference_title: "Integrative genomic profiling of large-cell neuroendocrine carcinomas reveals distinct subtypes of high-grade neuroendocrine lung tumors."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "with bi-allelic TP53 and STK11/KEAP1 alterations (37%)"
      explanation: Defines the type I branch as TP53 plus STK11/KEAP1 rather than TP53 plus RB1.
- name: Mutator Phenotype and Chromosomal Instability
  biological_scale: MOLECULAR
  role: central_effector
  conforms_to: "genome_instability_mutation#Mutator Phenotype and Chromosomal Instability"
  description: >-
    Following p53 loss, LCNEC accumulates a high mutation burden together with
    recurrent focal amplifications (MYCL1 at 1p34, FGFR1 at 8p12, MYC at 8q24.21,
    NKX2-1 at 14q13) and deletions (CDKN2A at 9p21), i.e. the mutator phenotype
    and chromosomal instability that the genome-instability module describes.
  biological_processes:
  - preferred_term: DNA repair
    modifier: DECREASED
    term:
      id: GO:0006281
      label: DNA repair
  evidence:
  - reference: PMID:29535388
    reference_title: "Integrative genomic profiling of large-cell neuroendocrine carcinomas reveals distinct subtypes of high-grade neuroendocrine lung tumors."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Analyses of chromosomal gene copy numbers revealed statistically significant amplifications of 1p34 (containing the MYCL1 gene, 12%), 8p12 (containing FGFR1, 7%), 8q24.21 (containing MYC, 5%)"
    explanation: Documents the recurrent copy-number changes that constitute chromosomal instability in LCNEC.
  - reference: PMID:35641209
    reference_title: "Comprehensive Characterization of the Genomic Landscape in Chinese Pulmonary Neuroendocrine Tumors Reveals Prognostic and Therapeutic Markers (CSWOG-1901)."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Large cell neuroendocrine carcinoma (12.7 mutations/Mb) and SCLC (11.9 mutations/Mb) showed higher tumor mutational burdens than TC (2.4 mutations/Mb) and AC (7.1 mutations/Mb)"
    explanation: >-
      Quantifies the mutator phenotype, showing that LCNEC carries a tumour
      mutational burden comparable to SCLC and several-fold above the
      low- and intermediate-grade carcinoids.
  downstream:
  - target: High-Grade Proliferative Activity and Necrosis
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: Accumulated driver alterations converge on the high-grade proliferative phenotype.
- name: RB1 Biallelic Inactivation
  biological_scale: MOLECULAR
  role: central_effector
  description: >-
    Biallelic RB1 inactivation, co-occurring with TP53 loss, defines the
    SCLC-like (Rekhtman) or type II (George) subgroup. RB1 mutation is reported
    in 38-47% of cases and loss of nuclear Rb protein in up to 72%. This branch
    is mutually exclusive with the STK11/KEAP1 branch. Note the counterintuitive
    transcriptional consequence: despite the SCLC-like genotype, type II tumours
    show reduced neuroendocrine marker expression.
  genes:
  - preferred_term: RB1
    term:
      id: hgnc:9884
      label: RB1
  evidence:
  - reference: PMID:26960398
    reference_title: "Next-Generation Sequencing of Pulmonary Large Cell Neuroendocrine Carcinoma Reveals Small Cell Carcinoma-like and Non-Small Cell Carcinoma-like Subsets."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "SCLC-like (n = 18), characterized by TP53+RB1 co-mutation/loss and other SCLC-type alterations, including MYCL amplification"
    explanation: Defines the SCLC-like subset by TP53+RB1 co-alteration.
  - reference: PMID:29066508
    reference_title: "Molecular Subtypes of Pulmonary Large-cell Neuroendocrine Carcinoma Predict Chemotherapy Treatment Outcome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "RB1 mutation and protein loss were detected in 47% (n = 37) and 72% (n = 78) of the cases, respectively."
    explanation: Gives the frequency of RB1 mutation and of Rb protein loss in a registry-based LCNEC cohort.
  - reference: PMID:29535388
    reference_title: "Integrative genomic profiling of large-cell neuroendocrine carcinomas reveals distinct subtypes of high-grade neuroendocrine lung tumors."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "somatic alterations of RB1 and STK11/KEAP1 were detected in 82% of the cases (n = 49) and occurred in a mutually exclusive fashion"
    explanation: Establishes that the RB1 and STK11/KEAP1 branches are mutually exclusive.
  - reference: PMID:38159439
    reference_title: "Real-World comprehensive genomic profiling data for diagnostic clarity in pulmonary Large-Cell neuroendocrine carcinoma."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The presence of RB1 and TP53 genomic alterations (GAs) were used to define a SCLC-like subtype (n = 557)."
    explanation: >-
      Confirms the TP53+RB1 SCLC-like subtype in a 1,426-sample clinical
      comprehensive genomic profiling series, far larger than the original
      discovery cohorts.
  downstream:
  - target: Loss of G1/S Cell-Cycle Checkpoint Control
    causal_link_type: DIRECT
    description: Loss of the Rb brake releases the G1/S restriction point.
  - target: NOTCH Pathway Dysregulation
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: >-
      Type II (RB1-altered) tumours display a NOTCH-high, neuroendocrine-low
      transcriptional state; the mechanistic link between RB1 loss and NOTCH
      activity in LCNEC is correlative rather than established.
    evidence:
    - reference: PMID:29535388
      reference_title: "Integrative genomic profiling of large-cell neuroendocrine carcinomas reveals distinct subtypes of high-grade neuroendocrine lung tumors."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "type II LCNECs bear TP53 and RB1 alterations and differ from most SCLC tumors with reduced neuroendocrine markers, a pattern of ASCL1low/DLL3low/NOTCHhigh, and an upregulation of immune-related pathways"
      explanation: >-
        Reports the association of the RB1-altered subgroup with a NOTCH-high,
        neuroendocrine-low state. Curated as PARTIAL because the study
        establishes co-occurrence, not a causal mechanism.
- name: STK11 and KEAP1 Biallelic Inactivation
  biological_scale: MOLECULAR
  role: central_effector
  description: >-
    Biallelic inactivation of STK11 (LKB1) and/or KEAP1, in the absence of RB1
    co-alteration, defines the NSCLC-like (Rekhtman) or type I (George)
    subgroup. STK11 loss deregulates LKB1-AMPK-mTOR energy sensing and KEAP1 loss
    constitutively activates NRF2 antioxidant signalling. This branch frequently
    also carries activating KRAS mutations.
  genes:
  - preferred_term: STK11
    term:
      id: hgnc:11389
      label: STK11
  - preferred_term: KEAP1
    term:
      id: hgnc:23177
      label: KEAP1
  - preferred_term: KRAS
    term:
      id: hgnc:6407
      label: KRAS
  evidence:
  - reference: PMID:26960398
    reference_title: "Next-Generation Sequencing of Pulmonary Large Cell Neuroendocrine Carcinoma Reveals Small Cell Carcinoma-like and Non-Small Cell Carcinoma-like Subsets."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "NSCLC-like (n = 25), characterized by the lack of coaltered TP53+RB1 and nearly universal occurrence of NSCLC-type mutations (STK11, KRAS, and KEAP1)"
    explanation: Defines the NSCLC-like subset by STK11/KRAS/KEAP1 alteration without TP53+RB1 co-alteration.
  - reference: PMID:29535388
    reference_title: "Integrative genomic profiling of large-cell neuroendocrine carcinomas reveals distinct subtypes of high-grade neuroendocrine lung tumors."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Combined with loss-of-heterozygosity (LOH), bi-allelic alterations of STK11 and KEAP1 were found in 37% of the cases"
    explanation: Quantifies biallelic STK11/KEAP1 alteration as the defining lesion of the type I subgroup.
  - reference: PMID:38159439
    reference_title: "Real-World comprehensive genomic profiling data for diagnostic clarity in pulmonary Large-Cell neuroendocrine carcinoma."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "These NSCLC-like subtype-defining GAs included SMARCA4, KRAS, FGF3/4/19, STK11, CDKN2A/B, MTAP, and CCND1."
    explanation: >-
      Extends the NSCLC-like lesion set beyond STK11/KEAP1/KRAS in a large
      clinical genomic profiling cohort.
  downstream:
  - target: Neuroendocrine Lineage Programme Expression
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: >-
      The type I subgroup retains a high neuroendocrine transcriptional
      programme (ASCL1-high, DLL3-high, NOTCH-low). The association is
      transcriptomic; no causal mechanism from STK11/KEAP1 loss to lineage state
      has been demonstrated in LCNEC.
    evidence:
    - reference: PMID:29535388
      reference_title: "Integrative genomic profiling of large-cell neuroendocrine carcinomas reveals distinct subtypes of high-grade neuroendocrine lung tumors."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "While type I LCNECs and SCLCs exhibit a neuroendocrine profile with ASCL1high/DLL3high/NOTCHlow"
      explanation: >-
        Associates the type I subgroup with the high-neuroendocrine
        transcriptional state. PARTIAL because the link is correlative.
- name: Loss of G1/S Cell-Cycle Checkpoint Control
  biological_scale: CELLULAR
  role: central_effector
  conforms_to: "evading_growth_suppressors#Loss of Cell-Cycle Checkpoint Control"
  description: >-
    Combined TP53 and RB1 inactivation removes both the p53 damage checkpoint and
    the Rb-enforced G1/S restriction point, the canonical
    evading-growth-suppressors lesion. In LCNEC this is the SCLC-like branch and
    is accompanied by measurably higher proliferative activity than in the
    STK11/KEAP1 branch.
  biological_processes:
  - preferred_term: G1/S transition of mitotic cell cycle
    modifier: INCREASED
    term:
      id: GO:0000082
      label: G1/S transition of mitotic cell cycle
  evidence:
  - reference: PMID:26960398
    reference_title: "Next-Generation Sequencing of Pulmonary Large Cell Neuroendocrine Carcinoma Reveals Small Cell Carcinoma-like and Non-Small Cell Carcinoma-like Subsets."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "higher proliferative activity in SCLC-like tumors (P < 0.0001)"
    explanation: Demonstrates that the TP53+RB1 branch translates into a measurably higher proliferative rate.
  downstream:
  - target: High-Grade Proliferative Activity and Necrosis
    causal_link_type: DIRECT
    description: Loss of checkpoint control produces the defining high mitotic rate.
- name: Neuroendocrine Lineage Programme Expression
  biological_scale: CELLULAR
  role: central_effector
  description: >-
    LCNEC expresses a neuroendocrine differentiation programme demonstrable as
    chromogranin A, synaptophysin and CD56 immunoreactivity, and
    transcriptionally as ASCL1 and DLL3 expression in the neuroendocrine-high
    subgroup. This programme, not the genomic lesion set, is what places LCNEC
    transcriptionally closest to small cell lung carcinoma and justifies its WHO
    classification as a neuroendocrine carcinoma rather than an NSCLC variant.
    DLL3 expression in this branch is the rationale for DLL3-directed therapy.
  cell_types:
  - preferred_term: pulmonary neuroendocrine cell
    term:
      id: CL:1000223
      label: pulmonary neuroendocrine cell
  biological_processes:
  - preferred_term: neuroendocrine cell differentiation
    term:
      id: GO:0061101
      label: neuroendocrine cell differentiation
  genes:
  - preferred_term: ASCL1
    term:
      id: hgnc:738
      label: ASCL1
  - preferred_term: DLL3
    term:
      id: hgnc:2909
      label: DLL3
  evidence:
  - reference: PMID:29535388
    reference_title: "Integrative genomic profiling of large-cell neuroendocrine carcinomas reveals distinct subtypes of high-grade neuroendocrine lung tumors."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "instead LCNECs form distinct transcriptional subgroups with closest similarity to SCLC"
    explanation: Establishes that LCNEC's transcriptional identity is neuroendocrine and SCLC-proximate.
  - reference: PMID:30485478
    reference_title: "Is the sum of positive neuroendocrine immunohistochemical stains useful for diagnosis of large cell neuroendocrine carcinoma (LCNEC) on biopsy specimens?"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "positive staining for greater than or equal to two of three neuroendocrine IHC markers increased the sensitivity for LCNEC from 47% to 93% on paired biopsy specimens"
    explanation: Shows that the neuroendocrine programme is demonstrable immunohistochemically and is diagnostically decisive.
  downstream:
  - target: High-Grade Proliferative Activity and Necrosis
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: >-
      The neuroendocrine programme accompanies, rather than causes, the
      high-grade phenotype; both are required for the diagnosis.
- name: NOTCH Pathway Dysregulation
  biological_scale: MOLECULAR
  role: modifier
  description: >-
    Inactivating NOTCH-family mutations occur in about a quarter of NSCLC-like
    LCNEC, and NOTCH pathway activity is high in the type II subgroup that shows
    low neuroendocrine marker expression. NOTCH signalling is an established
    regulator of the neuroendocrine-versus-non-neuroendocrine fate switch in lung
    epithelium, which makes it the most plausible link between the genomic
    subgroups and their divergent lineage states.
  biological_processes:
  - preferred_term: Notch signaling pathway
    term:
      id: GO:0007219
      label: Notch signaling pathway
  evidence:
  - reference: PMID:26960398
    reference_title: "Next-Generation Sequencing of Pulmonary Large Cell Neuroendocrine Carcinoma Reveals Small Cell Carcinoma-like and Non-Small Cell Carcinoma-like Subsets."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "more frequent mutations in NOTCH family genes (28%), implicated as key regulators of neuroendocrine differentiation"
    explanation: Quantifies NOTCH-family mutation in LCNEC and names its role in neuroendocrine differentiation.
  downstream:
  - target: Neuroendocrine Lineage Programme Expression
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: >-
      NOTCH activity is inversely associated with neuroendocrine marker
      expression across the LCNEC subgroups.
- name: High-Grade Proliferative Activity and Necrosis
  biological_scale: CELLULAR
  role: central_effector
  description: >-
    A mitotic rate above 10 mitoses per 2 square millimetres together with
    extensive, often geographic necrosis is a defining diagnostic criterion of
    LCNEC and separates it from the low-grade (typical carcinoid) and
    intermediate-grade (atypical carcinoid) neuroendocrine tumours.
  biological_processes:
  - preferred_term: cell population proliferation
    modifier: INCREASED
    term:
      id: GO:0008283
      label: cell population proliferation
  evidence:
  - reference: PMID:28572122
    reference_title: "Chemotherapy for pulmonary large cell neuroendocrine carcinomas: does the regimen matter?"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "a subtype of lung cancer with neuroendocrine morphology, neuroendocrine differentiation on immunohistochemistry, a high mitotic rate"
    explanation: States the defining combination of neuroendocrine features with a high mitotic rate.
  downstream:
  - target: Local Tumour Growth with Central or Peripheral Presentation
    causal_link_type: DIRECT
    description: Unrestrained proliferation produces the expanding primary mass.
  - target: Early Metastatic Dissemination
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: The high-grade phenotype underlies the characteristic early and widespread dissemination.
- name: Local Tumour Growth with Central or Peripheral Presentation
  biological_scale: TISSUE
  role: consequence
  description: >-
    The primary tumour grows as either a peripheral mass, which is the majority
    pattern, or a central tumour invading the segmental or lobar bronchus. The
    distinction is prognostically and biologically real: central tumours are more
    strongly associated with smoking, present at higher stage and larger size,
    and carry markedly worse survival, while peripheral tumours more often retain
    Rb protein and harbour EGFR mutations.
  cell_types:
  - preferred_term: bronchial epithelial cell
    term:
      id: CL:0002328
      label: bronchial epithelial cell
  evidence:
  - reference: PMID:29413048
    reference_title: "Distinct clinicopathologic features, genomic characteristics and survival of central and peripheral pulmonary large cell neuroendocrine carcinoma: From different origin cells?"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The tumors with invasion of the segmental and/or lobar bronchus were classified as central LCNEC and those without as peripheral LCNEC."
    explanation: Defines the central versus peripheral growth patterns by bronchial invasion.
  - reference: PMID:29413048
    reference_title: "Distinct clinicopathologic features, genomic characteristics and survival of central and peripheral pulmonary large cell neuroendocrine carcinoma: From different origin cells?"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The majority of LCNEC proved to be of the peripheral type (64.3%, 81/126). Central tumors were associated with smoking habit (p = 0.047), higher TNM-stage (p = 0.014) and larger tumor size (p < 0.001)."
    explanation: Quantifies the peripheral predominance and the clinical correlates of central growth.
  downstream:
  - target: Lung Neoplasm
    causal_link_type: DIRECT
    description: The expanding primary constitutes the clinically detected lung neoplasm.
- name: Early Metastatic Dissemination
  biological_scale: ORGANISM
  role: consequence
  conforms_to: "invasion_and_metastasis#Metastatic Colonization"
  description: >-
    LCNEC disseminates early and widely. In population data the majority of
    patients present at stage IV, and brain metastasis is more frequent than in
    either small cell or non-small cell lung cancer, making the central nervous
    system a characteristic site of colonisation.
  evidence:
  - reference: PMID:31601526
    reference_title: "Large-Cell Neuroendocrine Carcinoma of the Lung: A Population-Based Study."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "LCNEC was more common among male subjects, and disease usually presented at stage IV (55%)"
    explanation: Establishes that most patients present with disseminated disease.
  - reference: PMID:31601526
    reference_title: "Large-Cell Neuroendocrine Carcinoma of the Lung: A Population-Based Study."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Brain metastasis occurred more frequently in LCNEC (19.2%) than SCLC (16.7%, P < .001) or NSCLC (13%, P < .001)"
    explanation: Documents the disproportionate brain tropism of LCNEC.
  downstream:
  - target: Brain Metastasis
    causal_link_type: DIRECT
    description: >-
      Colonisation of the central nervous system produces the brain metastases
      that are disproportionately frequent in LCNEC.
phenotypes:
- category: Neoplastic
  name: Lung Neoplasm
  description: >-
    The pulmonary primary tumour, most often presenting as a peripheral mass but
    with a substantial minority arising centrally.
  phenotype_term:
    preferred_term: Neoplasm of the lung
    term:
      id: HP:0100526
      label: Neoplasm of the lung
  frequency: VERY_FREQUENT
  evidence:
  - reference: PMID:31601526
    reference_title: "Large-Cell Neuroendocrine Carcinoma of the Lung: A Population-Based Study."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Large-cell neuroendocrine carcinoma (LCNEC) accounts for approximately 3% of lung malignancies."
    explanation: Establishes LCNEC as a lung malignancy in the dominant pulmonary form.
- category: Neurologic
  name: Brain Metastasis
  description: >-
    Metastatic involvement of the brain, disproportionately frequent in LCNEC
    compared with both small cell and non-small cell lung cancer.
  phenotype_term:
    preferred_term: Brain neoplasm
    term:
      id: HP:0030692
      label: Brain neoplasm
  frequency: OCCASIONAL
  evidence:
  - reference: PMID:31601526
    reference_title: "Large-Cell Neuroendocrine Carcinoma of the Lung: A Population-Based Study."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Brain metastasis occurred more frequently in LCNEC (19.2%) than SCLC (16.7%, P < .001) or NSCLC (13%, P < .001)"
    explanation: >-
      Reports brain metastasis in 19.2% of LCNEC, which maps to the OCCASIONAL
      band (5-29%).
histopathology:
- name: Neuroendocrine Morphology with High Mitotic Rate and Necrosis
  description: >-
    Organoid nesting, palisading and rosette-like structures with large cells,
    abundant cytoplasm and prominent nucleoli, combined with a mitotic rate above
    10 per 2 square millimetres and extensive necrosis. Neuroendocrine morphology
    is frequently not appreciable on small biopsies, which is the main reason
    LCNEC is underdiagnosed pre-operatively.
  evidence:
  - reference: PMID:30485478
    reference_title: "Is the sum of positive neuroendocrine immunohistochemical stains useful for diagnosis of large cell neuroendocrine carcinoma (LCNEC) on biopsy specimens?"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Neuroendocrine morphology was absent in 53% (n = 17 of 32) of paired biopsy specimens"
    explanation: Quantifies how often the defining morphology is missing on biopsy material.
  - reference: PMID:30485478
    reference_title: "Is the sum of positive neuroendocrine immunohistochemical stains useful for diagnosis of large cell neuroendocrine carcinoma (LCNEC) on biopsy specimens?"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "LCNEC is difficult to diagnose because neuroendocrine morphology is frequently absent in biopsy specimens."
    explanation: States the diagnostic consequence of the morphology being biopsy-dependent.
genetic:
- name: TP53
  gene_term:
    preferred_term: TP53
    term:
      id: hgnc:11998
      label: TP53
  relationship_type: SOMATIC_DRIVER
  variant_origin: SOMATIC
  frequency: near-universal
  case_fractions:
  - population: European genomic LCNEC cohort (Cologne, whole-exome/genome sequencing)
    case_fraction_percent: 92.0
    cohort_size: 60
    notes: Most frequently mutated gene in the sequenced cohort.
    evidence:
    - reference: PMID:29535388
      reference_title: "Integrative genomic profiling of large-cell neuroendocrine carcinomas reveals distinct subtypes of high-grade neuroendocrine lung tumors."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "TP53 was the most frequently mutated gene (92%)"
      explanation: Quantifies the TP53-altered share of cases in the European genomic cohort.
  - population: US targeted-sequencing LCNEC cohort (MSK-IMPACT)
    case_fraction_percent: 78.0
    cohort_size: 45
    evidence:
    - reference: PMID:26960398
      reference_title: "Next-Generation Sequencing of Pulmonary Large Cell Neuroendocrine Carcinoma Reveals Small Cell Carcinoma-like and Non-Small Cell Carcinoma-like Subsets."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "Commonly altered genes in LCNEC included TP53 (78%), RB1 (38%), STK11 (33%), KEAP1 (31%), and KRAS (22%)"
      explanation: Quantifies the TP53-altered share of cases in the MSK-IMPACT cohort.
  evidence:
  - reference: PMID:29535388
    reference_title: "Integrative genomic profiling of large-cell neuroendocrine carcinomas reveals distinct subtypes of high-grade neuroendocrine lung tumors."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "TP53 was the most frequently mutated gene (92%)"
    explanation: Establishes TP53 as the most frequently altered gene in LCNEC.
- name: RB1
  gene_term:
    preferred_term: RB1
    term:
      id: hgnc:9884
      label: RB1
  relationship_type: SOMATIC_DRIVER
  variant_origin: SOMATIC
  frequency: defining lesion of the SCLC-like/type II subgroup
  case_fractions:
  - population: Dutch national registry LCNEC cohort (panel-consensus revised, NGS subset)
    case_fraction_percent: 47.0
    cohort_size: 79
    notes: >-
      RB1 mutation by next-generation sequencing. RB1 protein loss by
      immunohistochemistry was more common (72%, n = 78 of 109 stained cases),
      so the immunohistochemical share exceeds the mutational one.
    evidence:
    - reference: PMID:29066508
      reference_title: "Molecular Subtypes of Pulmonary Large-cell Neuroendocrine Carcinoma Predict Chemotherapy Treatment Outcome."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "RB1 mutation and protein loss were detected in 47% (n = 37) and 72% (n = 78) of the cases, respectively."
      explanation: Quantifies the RB1-mutated share of cases in the Dutch registry cohort.
  - population: US targeted-sequencing LCNEC cohort (MSK-IMPACT)
    case_fraction_percent: 38.0
    cohort_size: 45
    evidence:
    - reference: PMID:26960398
      reference_title: "Next-Generation Sequencing of Pulmonary Large Cell Neuroendocrine Carcinoma Reveals Small Cell Carcinoma-like and Non-Small Cell Carcinoma-like Subsets."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "Commonly altered genes in LCNEC included TP53 (78%), RB1 (38%), STK11 (33%), KEAP1 (31%), and KRAS (22%)"
      explanation: Quantifies the RB1-altered share of cases in the MSK-IMPACT cohort.
  evidence:
  - reference: PMID:29066508
    reference_title: "Molecular Subtypes of Pulmonary Large-cell Neuroendocrine Carcinoma Predict Chemotherapy Treatment Outcome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "RB1 mutation and protein loss were detected in 47% (n = 37) and 72% (n = 78) of the cases, respectively."
    explanation: Gives RB1 mutation and protein-loss frequencies in a national registry cohort.
- name: STK11
  gene_term:
    preferred_term: STK11
    term:
      id: hgnc:11389
      label: STK11
  relationship_type: SOMATIC_DRIVER
  variant_origin: SOMATIC
  case_fractions:
  - population: US targeted-sequencing LCNEC cohort (MSK-IMPACT)
    case_fraction_percent: 33.0
    cohort_size: 45
    evidence:
    - reference: PMID:26960398
      reference_title: "Next-Generation Sequencing of Pulmonary Large Cell Neuroendocrine Carcinoma Reveals Small Cell Carcinoma-like and Non-Small Cell Carcinoma-like Subsets."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "Commonly altered genes in LCNEC included TP53 (78%), RB1 (38%), STK11 (33%), KEAP1 (31%), and KRAS (22%)"
      explanation: Quantifies the STK11-altered share of cases in the MSK-IMPACT cohort.
  evidence:
  - reference: PMID:26960398
    reference_title: "Next-Generation Sequencing of Pulmonary Large Cell Neuroendocrine Carcinoma Reveals Small Cell Carcinoma-like and Non-Small Cell Carcinoma-like Subsets."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Commonly altered genes in LCNEC included TP53 (78%), RB1 (38%), STK11 (33%), KEAP1 (31%), and KRAS (22%)"
    explanation: Reports STK11 alteration in 33% of LCNEC.
- name: KEAP1
  gene_term:
    preferred_term: KEAP1
    term:
      id: hgnc:23177
      label: KEAP1
  relationship_type: SOMATIC_DRIVER
  variant_origin: SOMATIC
  case_fractions:
  - population: US targeted-sequencing LCNEC cohort (MSK-IMPACT)
    case_fraction_percent: 31.0
    cohort_size: 45
    evidence:
    - reference: PMID:26960398
      reference_title: "Next-Generation Sequencing of Pulmonary Large Cell Neuroendocrine Carcinoma Reveals Small Cell Carcinoma-like and Non-Small Cell Carcinoma-like Subsets."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "Commonly altered genes in LCNEC included TP53 (78%), RB1 (38%), STK11 (33%), KEAP1 (31%), and KRAS (22%)"
      explanation: Quantifies the KEAP1-altered share of cases in the MSK-IMPACT cohort.
  evidence:
  - reference: PMID:26960398
    reference_title: "Next-Generation Sequencing of Pulmonary Large Cell Neuroendocrine Carcinoma Reveals Small Cell Carcinoma-like and Non-Small Cell Carcinoma-like Subsets."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Commonly altered genes in LCNEC included TP53 (78%), RB1 (38%), STK11 (33%), KEAP1 (31%), and KRAS (22%)"
    explanation: Reports KEAP1 alteration in 31% of LCNEC.
- name: KRAS
  gene_term:
    preferred_term: KRAS
    term:
      id: hgnc:6407
      label: KRAS
  relationship_type: SOMATIC_DRIVER
  variant_origin: SOMATIC
  case_fractions:
  - population: US targeted-sequencing LCNEC cohort (MSK-IMPACT)
    case_fraction_percent: 22.0
    cohort_size: 45
    evidence:
    - reference: PMID:26960398
      reference_title: "Next-Generation Sequencing of Pulmonary Large Cell Neuroendocrine Carcinoma Reveals Small Cell Carcinoma-like and Non-Small Cell Carcinoma-like Subsets."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "Commonly altered genes in LCNEC included TP53 (78%), RB1 (38%), STK11 (33%), KEAP1 (31%), and KRAS (22%)"
      explanation: Quantifies the KRAS-altered share of cases in the MSK-IMPACT cohort.
  evidence:
  - reference: PMID:26960398
    reference_title: "Next-Generation Sequencing of Pulmonary Large Cell Neuroendocrine Carcinoma Reveals Small Cell Carcinoma-like and Non-Small Cell Carcinoma-like Subsets."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Commonly altered genes in LCNEC included TP53 (78%), RB1 (38%), STK11 (33%), KEAP1 (31%), and KRAS (22%)"
    explanation: Reports KRAS mutation in 22% of LCNEC, within the NSCLC-like branch.
environmental:
- name: Tobacco smoking
  description: >-
    Heavy tobacco smoking is the dominant environmental risk factor for pulmonary
    LCNEC. Sequencing confirms a dominant tobacco mutational signature in these
    tumours.
  influences_mechanisms:
  - target: Tobacco Carcinogen Exposure and Smoking-Associated Mutagenesis
    environmental_effect: TRIGGERS
    causal_link_type: DIRECT
    description: >-
      Chronic smoking is the exposure that generates the carcinogen-driven
      mutational process initiating LCNEC.
    evidence:
    - reference: PMID:29535388
      reference_title: "Integrative genomic profiling of large-cell neuroendocrine carcinomas reveals distinct subtypes of high-grade neuroendocrine lung tumors."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "LCNEC and SCLC are clinically aggressive tumors presenting in elderly heavy-smokers"
      explanation: Establishes heavy smoking as the population context in which LCNEC arises.
  evidence:
  - reference: PMID:29535388
    reference_title: "Integrative genomic profiling of large-cell neuroendocrine carcinomas reveals distinct subtypes of high-grade neuroendocrine lung tumors."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "which confirmed a prominent smoking-related signature (signature 4"
    explanation: Confirms the tobacco mutational signature as the dominant mutational process in LCNEC.
  notes: >-
    Left without an `exposure_term` binding pending an ECTO lookup for a
    tobacco-smoke exposure class; the mechanism link is what places this exposure
    in the pathograph.
prevalence:
- population: United States (SEER 2010-2015, lung primaries)
  measure_type: POINT_PREVALENCE
  prevalence_class: RARE
  notes: >-
    LCNEC accounted for 1681 of 195,148 lung cancer cases (0.9%) in SEER
    2010-2015. Other series place it at approximately 3% of lung malignancies;
    the difference reflects registry coding versus panel-reviewed pathology, and
    LCNEC is known to be underdiagnosed on biopsy. Recorded as a proportion of
    lung cancers, not as a population rate, because the sources report it that
    way.
  evidence:
  - reference: PMID:31601526
    reference_title: "Large-Cell Neuroendocrine Carcinoma of the Lung: A Population-Based Study."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "A total of 195,148 cases of lung cancer, including 1681 (0.9%) cases of LCNEC, were analyzed."
    explanation: Gives the registry-based share of lung cancers diagnosed as LCNEC.
- population: Resected lung cancers (European genomic cohort)
  measure_type: POINT_PREVALENCE
  prevalence_class: RARE
  notes: LCNEC as a proportion of resected lung cancers.
  evidence:
  - reference: PMID:29535388
    reference_title: "Integrative genomic profiling of large-cell neuroendocrine carcinomas reveals distinct subtypes of high-grade neuroendocrine lung tumors."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "LCNECs account for 2–3% of all resected lung cancers"
    explanation: Independent estimate of LCNEC frequency among resected lung cancers.
epidemiology:
- name: Rising incidence and mortality
  description: >-
    The recorded incidence of LCNEC has been rising, driven mainly by stage IV
    disease, and annual mortality doubled over the period studied in SEER. Part
    of this trend may reflect improving pathological recognition rather than
    changing biology; see the under-diagnosis knowledge gap.
  evidence:
  - reference: PMID:31601526
    reference_title: "Large-Cell Neuroendocrine Carcinoma of the Lung: A Population-Based Study."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Incidence increased by 0.011 people per 100,000 per year, primarily of stage IV disease. Annual mortality from LCNEC doubled over the time period studied."
    explanation: Documents the rising incidence and mortality of LCNEC.
- name: Marked male predominance and later-middle-age onset
  description: >-
    A single-centre surgical series of 62 patients was 95% male with a mean age
    of 60.3 years, an extreme sex skew consistent with the historical
    distribution of heavy smoking. Registry data show the same direction of
    effect more moderately, so the 95% figure should be read as a single-centre
    observation rather than a population estimate.
  evidence:
  - reference: PMID:32584230
    reference_title: "Characteristics of Patients with Large-Cell Neuroendocrine Carcinoma of the Lung."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The patients were predominantly (95%) men (male:female=59:3) with their average age being 60.3±8.6 years."
    explanation: Gives the sex ratio and mean age at diagnosis in a surgical LCNEC series.
- name: Survival by central versus peripheral tumour location
  description: >-
    Tumour location is a strong independent prognostic factor, with peripheral
    tumours surviving markedly longer than central ones.
  evidence:
  - reference: PMID:29413048
    reference_title: "Distinct clinicopathologic features, genomic characteristics and survival of central and peripheral pulmonary large cell neuroendocrine carcinoma: From different origin cells?"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Peripheral tumors had better survival compared with central tumors (median OS: 4.04 vs. 1.51 years, p < 0.001)."
    explanation: Quantifies the survival difference between central and peripheral LCNEC.
progression:
- phase: Stage-dependent divergent clinical behaviour
  notes: >-
    An unusual and clinically important feature of LCNEC is that its natural
    history tracks non-small cell lung cancer at stages I-III but small cell lung
    cancer at stage IV. Overall survival is poor, with five-year survival below
    15-25% in genomically characterised cohorts.
  evidence:
  - reference: PMID:31601526
    reference_title: "Large-Cell Neuroendocrine Carcinoma of the Lung: A Population-Based Study."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Survival in patients with stage I-III LCNEC mirrored survival trends of patients with NSCLC, whereas stage IV LCNEC behaved similarly to SCLC."
    explanation: States the stage-dependent divergence in clinical behaviour.
  - reference: PMID:29535388
    reference_title: "Integrative genomic profiling of large-cell neuroendocrine carcinomas reveals distinct subtypes of high-grade neuroendocrine lung tumors."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "with 5-year survival rates below 15–25% (LCNEC) and 5% (SCLC), respectively"
    explanation: Gives the five-year survival range for LCNEC.
diagnosis:
- name: Combined morphologic and immunohistochemical diagnosis
  description: >-
    Diagnosis requires neuroendocrine morphology, a high mitotic rate and
    neuroendocrine differentiation confirmed by immunohistochemistry (CD56,
    chromogranin A, synaptophysin). Because neuroendocrine morphology is often
    absent on small biopsies, positivity for at least two of three neuroendocrine
    markers substantially improves sensitivity and is the practical diagnostic
    rule on biopsy material.
  evidence:
  - reference: PMID:30485478
    reference_title: "Is the sum of positive neuroendocrine immunohistochemical stains useful for diagnosis of large cell neuroendocrine carcinoma (LCNEC) on biopsy specimens?"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "In NSCLC devoid of obvious morphological squamous or adenocarcinoma features, positive staining in greater than or equal to two of three neuroendocrine IHC stains supports the diagnosis of LCNEC."
    explanation: States the operational immunohistochemical diagnostic rule for biopsy specimens.
  - reference: PMID:30485478
    reference_title: "Is the sum of positive neuroendocrine immunohistochemical stains useful for diagnosis of large cell neuroendocrine carcinoma (LCNEC) on biopsy specimens?"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "further validated using an independent TMA of LCNEC and NSCLC with sensitivity and specificity of 80% and 99%, respectively"
    explanation: Gives the validated performance of the two-of-three marker rule.
differential_diagnoses:
- name: Small cell lung carcinoma
  description: >-
    The principal differential. SCLC shares neuroendocrine differentiation and
    the TP53+RB1 genotype but differs in cytology (small cells, scant cytoplasm,
    nuclear moulding, inconspicuous nucleoli). Transcriptionally LCNEC sits
    closest to SCLC, which is why the distinction rests on cytomorphology rather
    than on marker expression.
  disease_term:
    preferred_term: small cell lung carcinoma
    term:
      id: MONDO:0008433
      label: small cell lung carcinoma
  evidence:
  - reference: PMID:29535388
    reference_title: "Integrative genomic profiling of large-cell neuroendocrine carcinomas reveals distinct subtypes of high-grade neuroendocrine lung tumors."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "instead LCNECs form distinct transcriptional subgroups with closest similarity to SCLC"
    explanation: Establishes the transcriptional proximity that makes SCLC the key differential.
- name: Atypical carcinoid
  description: >-
    The intermediate-grade neuroendocrine tumour. Shares neuroendocrine
    morphology and marker expression but is separated from LCNEC by mitotic rate
    and necrosis; a small minority of LCNEC-diagnosed tumours are genomically
    carcinoid-like, which is a recognised classification boundary problem.
  evidence:
  - reference: PMID:26960398
    reference_title: "Next-Generation Sequencing of Pulmonary Large Cell Neuroendocrine Carcinoma Reveals Small Cell Carcinoma-like and Non-Small Cell Carcinoma-like Subsets."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "and carcinoid-like (n = 2), characterized by MEN1 mutations and low mutation burden"
    explanation: Documents the genomically carcinoid-like minority within histologically diagnosed LCNEC.
treatments:
- name: Platinum-Etoposide Chemotherapy
  description: >-
    Small cell lung cancer-type chemotherapy, historically the default first-line
    regimen for advanced LCNEC by extrapolation from SCLC. Note that its
    superiority is not established, and in RB1 wild-type tumours it performs
    worse than NSCLC-type chemotherapy.
  treatment_term:
    preferred_term: chemotherapy
    term:
      id: NCIT:C15632
      label: Chemotherapy
    therapeutic_agent:
    - preferred_term: cisplatin
      term:
        id: CHEBI:27899
        label: cisplatin
    - preferred_term: carboplatin
      term:
        id: CHEBI:31355
        label: carboplatin
    - preferred_term: etoposide
      term:
        id: CHEBI:4911
        label: etoposide
  therapeutic_modality: SMALL_MOLECULE
  target_mechanisms:
  - target: High-Grade Proliferative Activity and Necrosis
    treatment_effect: INHIBITS
    description: >-
      Cytotoxic chemotherapy targets the rapidly proliferating compartment that
      defines the high-grade phenotype.
    evidence:
    - reference: PMID:34513663
      reference_title: "Management of Large Cell Neuroendocrine Carcinoma."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "the historical regimen of platinum based therapy in combination with etoposide or irinotecan remains among the commonly used first line therapies"
      explanation: Establishes platinum-etoposide as a standard first-line cytotoxic regimen in advanced LCNEC.
  evidence:
  - reference: PMID:34513663
    reference_title: "Management of Large Cell Neuroendocrine Carcinoma."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "In advanced disease, the historical regimen of platinum based therapy in combination with etoposide or irinotecan remains among the commonly used first line therapies"
    explanation: Documents the standard-of-care status of platinum-etoposide in advanced LCNEC.
- name: NSCLC-Type Platinum Doublet Chemotherapy
  description: >-
    Platinum combined with gemcitabine or a taxane. In a national registry cohort
    this produced longer overall survival than either pemetrexed-based or
    etoposide-based treatment, and in RB1 wild-type tumours it significantly
    outperformed platinum-etoposide. This is the clearest example in LCNEC of
    molecular subtype guiding chemotherapy choice.
  treatment_term:
    preferred_term: chemotherapy
    term:
      id: NCIT:C15632
      label: Chemotherapy
    therapeutic_agent:
    - preferred_term: gemcitabine
      term:
        id: CHEBI:175901
        label: gemcitabine
    - preferred_term: paclitaxel
      term:
        id: CHEBI:45863
        label: paclitaxel
  therapeutic_modality: SMALL_MOLECULE
  target_mechanisms:
  - target: High-Grade Proliferative Activity and Necrosis
    treatment_effect: INHIBITS
    description: >-
      Cytotoxic chemotherapy targets the proliferating tumour compartment. RB1
      status does not change the drug target but predicts which cytotoxic
      strategy performs better.
    evidence:
    - reference: PMID:29066508
      reference_title: "Molecular Subtypes of Pulmonary Large-cell Neuroendocrine Carcinoma Predict Chemotherapy Treatment Outcome."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "Patients with LCNEC tumors that carry a wild-type RB1 gene or express the RB1 protein do better with NSCLC-GEM/TAX treatment than with SCLC-PE chemotherapy."
      explanation: Establishes RB1 status as predictive of differential benefit between the two chemotherapy strategies.
  evidence:
  - reference: PMID:29066508
    reference_title: "Molecular Subtypes of Pulmonary Large-cell Neuroendocrine Carcinoma Predict Chemotherapy Treatment Outcome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Patients with RB1 wild-type LCNEC treated with NSCLC-GEM/TAX had a significantly longer OS [9.6; 95% confidence interval (CI), 7.7-11.6 months] than those treated with SCLC-PE [5.8 (5.5-6.1); P = 0.026]"
    explanation: Gives the survival difference by RB1 status between NSCLC-type and SCLC-type chemotherapy.
  - reference: PMID:28572122
    reference_title: "Chemotherapy for pulmonary large cell neuroendocrine carcinomas: does the regimen matter?"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "In patients with LCNEC, NSCLC-t chemotherapy results in longer overall survival compared to NSCLC-pt and SCLC-t chemotherapy."
    explanation: Independent registry evidence that NSCLC-type chemotherapy gives the longest overall survival.
  notes: >-
    RB1 is a predictive biomarker here, not a drug target. The `target_mechanisms`
    link therefore points at the proliferative compartment the cytotoxics act on,
    and the RB1 relationship is carried by the evidence and this note.
- name: Dual Immune Checkpoint Blockade
  description: >-
    Ipilimumab plus nivolumab, studied prospectively in the high-grade
    neuroendocrine neoplasm cohort of the DART SWOG S1609 basket trial. Activity
    is real but modest, and the cohort was histologically and anatomically mixed
    rather than LCNEC-specific.
  treatment_term:
    preferred_term: Pharmacotherapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
    therapeutic_agent:
    - preferred_term: ipilimumab
      term:
        id: NCIT:C2654
        label: Ipilimumab
    - preferred_term: nivolumab
      term:
        id: NCIT:C68814
        label: Nivolumab
  therapeutic_modality: MONOCLONAL_ANTIBODY
  evidence:
  - reference: PMID:33882143
    reference_title: "A phase II basket trial of Dual Anti-CTLA-4 and Anti-PD-1 Blockade in Rare Tumors (DART) SWOG S1609: High-grade neuroendocrine neoplasm cohort."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Ipilimumab plus nivolumab demonstrated a 26% ORR in patients with high-grade neuroendocrine neoplasms, with durable responses seen in patients with refractory disease."
    explanation: >-
      Reports prospective activity of dual checkpoint blockade in high-grade
      neuroendocrine neoplasms. Curated as PARTIAL because the 19-patient cohort
      was not LCNEC-specific.
  notes: >-
    The trial enrolled high-grade neuroendocrine neoplasms of mixed primary site
    (most commonly unknown primary, rectum, gastro-oesophageal junction, cervix
    and pancreas), so this is extrapolated rather than direct LCNEC evidence.
- name: Surgical Resection
  description: >-
    Complete resection is the treatment of choice for early-stage, resectable
    LCNEC, consistent with the observation that stage I-III LCNEC behaves like
    non-small cell lung cancer.
  treatment_term:
    preferred_term: Surgical Procedure
    term:
      id: NCIT:C15329
      label: Surgical Procedure
  therapeutic_modality: SURGERY
  evidence:
  - reference: PMID:31601526
    reference_title: "Large-Cell Neuroendocrine Carcinoma of the Lung: A Population-Based Study."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Stage I-III LCNEC behaves similarly to NSCLC, whereas stage IV is more akin to SCLC."
    explanation: >-
      Supports an NSCLC-like, resection-oriented approach at stages I-III.
      PARTIAL because this population study reports behaviour rather than
      directly comparing surgical against non-surgical management.
- name: Site-Adapted Chemotherapy for Extrapulmonary LCNEC
  description: >-
    For extrathoracic primaries, gastrointestinal-type regimens are used in
    addition to the platinum backbone, reflecting the site rather than the
    pulmonary paradigm.
  treatment_term:
    preferred_term: chemotherapy
    term:
      id: NCIT:C15632
      label: Chemotherapy
  therapeutic_modality: SMALL_MOLECULE
  evidence:
  - reference: PMID:34513663
    reference_title: "Management of Large Cell Neuroendocrine Carcinoma."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "however for extra thoracic LCNEC regimens like FOLFOX, FOLFOIRI and CAPTEM can also be used"
    explanation: Documents the site-adapted chemotherapy options for extrapulmonary LCNEC.
animal_models:
- name: Quadruple tumour-suppressor knockout mouse (Rb1/Rbl1/Pten/Trp53)
  species: Mouse
  genotype: Rbl1-null; Rb1, Pten and Trp53 conditional alleles deleted by adenoviral Cre
  publication: PMID:31611390
  description: >-
    The first defined mouse model of LCNEC. In an Rbl1-null background, deletion
    of Rb1, Pten and Trp53 by broadly targeted Ad-CMVcre produces LCNEC, whereas
    the identical genetic lesion delivered to basal cells by Ad-K5cre produces
    small cell lung carcinoma instead. This makes cell of origin, not genotype,
    the determinant of which high-grade neuroendocrine carcinoma develops.
  modeled_mechanisms:
  - target: Loss of G1/S Cell-Cycle Checkpoint Control
    relationship: RECAPITULATES
    fidelity: MODERATE
    description: >-
      Combined Rb1/Rbl1/Trp53 inactivation reproduces the checkpoint-loss lesion
      that defines the SCLC-like branch of human LCNEC.
    limitations: >-
      The model adds Rbl1 (p130) and Pten inactivation, which are not
      established recurrent drivers of human LCNEC, so the genotype is broader
      than the human lesion set. The tumours are also induced synchronously in
      immunocompetent mice rather than arising through decades of carcinogen
      exposure.
    evidence:
    - reference: PMID:31611390
      reference_title: "Differential development of large-cell neuroendocrine or small-cell lung carcinoma upon inactivation of 4 tumor suppressor genes."
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: "In an Rbl1-null background, deletion of Rb1, Pten, and Trp53 floxed alleles after Ad-CMVcre infection in a wide variety of lung epithelial cells produces LCNEC."
      explanation: Establishes that this genotype and delivery route generate LCNEC in mice.
    - reference: PMID:31611390
      reference_title: "Differential development of large-cell neuroendocrine or small-cell lung carcinoma upon inactivation of 4 tumor suppressor genes."
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: "Molecular and transcriptomic analyses of both models revealed strong similarities to their human counterparts."
      explanation: Supports treating the model as informative for the human disease.
  - target: Neuroendocrine Lineage Programme Expression
    relationship: PARTIALLY_RECAPITULATES
    fidelity: MODERATE
    description: >-
      The model reproduces the neuroendocrine carcinoma lineage and shows that
      restricting the same lesions to basal cells yields SCLC instead, directly
      demonstrating cell-of-origin control of the neuroendocrine phenotype.
    limitations: >-
      The experiment establishes that cell of origin determines which tumour
      type arises, but it does not model the ASCL1/DLL3/NOTCH transcriptional
      subgrouping that distinguishes human type I from type II LCNEC.
    evidence:
    - reference: PMID:31611390
      reference_title: "Differential development of large-cell neuroendocrine or small-cell lung carcinoma upon inactivation of 4 tumor suppressor genes."
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: "Meanwhile, inactivation of these genes using Ad-K5cre in basal cells leads to the development of SCLC, thus differentially influencing the lung cancer type developed."
      explanation: Demonstrates cell-of-origin control over the resulting neuroendocrine carcinoma type.
  evidence:
  - reference: PMID:31611390
    reference_title: "Differential development of large-cell neuroendocrine or small-cell lung carcinoma upon inactivation of 4 tumor suppressor genes."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "So far, a defined model of LCNEC has not been reported."
    explanation: Establishes this as the first defined animal model of LCNEC.
discussions:
- discussion_id: lcnec_molecular_subtype_binary
  kind: KNOWLEDGE_GAP
  prompt: >-
    Does the type I / type II (or SCLC-like / NSCLC-like) molecular
    classification of LCNEC hold up as a binary, and should it direct first-line
    therapy prospectively?
  attaches_to:
  - "pathophysiology#RB1 Biallelic Inactivation"
  - "pathophysiology#STK11 and KEAP1 Biallelic Inactivation"
  rationale: >-
    The subgroup framework rests on retrospective cohorts, and the one
    treatment-relevant finding (RB1 wild-type tumours doing better with
    NSCLC-type than with SCLC-type chemotherapy) comes from a registry analysis,
    not a randomised trial. The two branches are reported as mutually exclusive
    in 82% of cases, which leaves a substantial residue that fits neither, and
    the discordance between the genomic label and the transcriptional phenotype
    suggests a continuum of neuroendocrine differentiation rather than two
    classes. The largest clinical genomic series to date makes the residue
    explicit: of 1,426 profiled LCNEC samples, 557 were SCLC-like, 530
    NSCLC-like, 25 carcinoid-like and 314 could not be classified at all. No
    prospective biomarker-stratified trial has yet tested assigning chemotherapy
    by RB1 status.
  evidence:
  - reference: PMID:38159439
    reference_title: "Real-World comprehensive genomic profiling data for diagnostic clarity in pulmonary Large-Cell neuroendocrine carcinoma."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Under this schema, 530 samples were classified as NSCLC-like and 314 remained unclassified."
    explanation: >-
      Quantifies the proportion of LCNEC that does not fit either genomic
      subtype, which is the empirical basis for treating the binary as
      incomplete.
  proposed_experiments:
  - experiment_id: lcnec_rb1_stratified_chemotherapy_trial
    name: Prospective RB1-stratified chemotherapy trial in advanced LCNEC
    description: >-
      Randomise patients with advanced LCNEC to platinum-etoposide versus
      platinum plus gemcitabine or taxane, stratified prospectively by RB1
      mutation and Rb immunohistochemistry, with overall survival as the primary
      endpoint.
- discussion_id: lcnec_underdiagnosis_epidemiology
  kind: KNOWLEDGE_GAP
  prompt: >-
    How much of the reported epidemiology of LCNEC is distorted by
    under-diagnosis on biopsy material?
  attaches_to:
  - "pathophysiology#Neuroendocrine Lineage Programme Expression"
  rationale: >-
    Neuroendocrine morphology is absent in roughly half of biopsies from tumours
    that prove to be LCNEC on resection, and registry-coded frequency (0.9% of
    lung cancers) is well below the pathology-reviewed estimate (about 3%).
    Population statistics on incidence, stage distribution and survival are
    therefore drawn from a systematically incomplete and probably
    resection-biased case set, and the apparent rise in incidence may partly
    reflect improving recognition rather than changing biology.
  proposed_experiments:
  - experiment_id: lcnec_population_pathology_rereview
    name: Central pathology re-review of a population-based lung cancer cohort
    description: >-
      Apply the validated two-of-three neuroendocrine immunohistochemistry rule
      to a consecutive population-based series of non-small cell lung cancers
      without obvious squamous or glandular differentiation, and compare the
      resulting LCNEC frequency and stage distribution against registry codes.
📚

References & Deep Research

References

2
PMID:26960398
Next-Generation Sequencing of Pulmonary Large Cell Neuroendocrine Carcinoma Reveals Small Cell Carcinoma-like and Non-Small Cell Carcinoma-like Subsets.
No top-level findings curated for this source.
PMID:29535388
Integrative genomic profiling of large-cell neuroendocrine carcinomas reveals distinct subtypes of high-grade neuroendocrine lung tumors.
No top-level findings curated for this source.

Deep Research

2
Claude Code ▸
Large Cell Neuroendocrine Carcinoma: A Comprehensive Research Report
claude-haiku-4-5-20251001, claude-sonnet-5 53 citations 2026-08-20T04:03:09.059276

Large Cell Neuroendocrine Carcinoma: A Comprehensive Research Report

1. Disease Information

Overview. Large cell neuroendocrine carcinoma (LCNEC) is a high-grade, poorly differentiated neuroendocrine carcinoma composed of large malignant epithelial cells that display neuroendocrine morphology (organoid nesting, palisading, rosette-like structures) together with high mitotic activity (>10 mitoses/2mm²) and often geographic necrosis (PathologyOutlines; Wikipedia). It was historically classified as a variant of large-cell lung carcinoma but is now recognized in the 2021 WHO Classification of Thoracic Tumours as one of two neuroendocrine carcinomas of the lung (alongside small cell lung carcinoma, SCLC), distinct from the low/intermediate-grade neuroendocrine tumors (typical and atypical carcinoid) (PathologyOutlines). Although the pulmonary form is the prototype and best studied, LCNEC also arises as a primary tumor in extrapulmonary sites — GI tract, pancreas, cervix, uterus, ovary, bladder, prostate, breast, larynx/pharynx, paranasal sinus, and thymus (Frontiers, Management of LCNEC, PMID:34513663; PMC10743506).

Key identifiers. - MONDO: MONDO:0018316-class term(s) for "large cell neuroendocrine carcinoma" (cross-referenced through the Monarch Initiative/NORD MONDO disease pages); the entity has organ-specific children (lung, breast, cervical, thymic, etc.) (NORD/MONDO). - ICD-O-3 morphology code: 8013/3 (Large cell neuroendocrine carcinoma). - ICD-11: 2C25.4 (malignant neuroendocrine neoplasms of bronchus or lung) with extension code XH0NL5 for large cell neuroendocrine carcinoma (AHA Coding Clinic). - ICD-10-CM: indexed under C34.- (malignant neoplasm of bronchus and lung) for the pulmonary primary, with topography-specific codes for extrapulmonary primaries. - MeSH: falls under "Carcinoma, Neuroendocrine" (D018277) and "Carcinoma, Large Cell" (D018281). - No dedicated OMIM or Orphanet entry exists specifically for sporadic LCNEC, as it is not a classical monogenic disorder; Orphanet does catalog rare neuroendocrine tumor syndromes (e.g., MEN1) that can predispose to related neuroendocrine neoplasia.

Synonyms/alternative names: Pulmonary large-cell neuroendocrine carcinoma (LCNEC, PLCNC); large cell/neuroendocrine carcinoma; high-grade neuroendocrine carcinoma (large cell type); "non-small cell neuroendocrine carcinoma" (older, discouraged terminology).

Data provenance. The evidence base combines: (1) aggregated population-level registry data (SEER, national cancer registries), (2) large retrospective single- and multi-institutional clinicopathologic cohorts, (3) integrative genomic/transcriptomic sequencing cohorts (tumor-level, not EHR-derived), and (4) a growing number of prospective clinical trials (phase II basket and single-arm trials). There is comparatively little large-scale EHR-based real-world evidence relative to more common cancers, reflecting LCNEC's rarity (~1–3% of all lung cancers) (PMC8081906).

2. Etiology

Disease Causal Factors

LCNEC does not have a single monogenic cause; it is a somatically acquired, multi-hit malignancy arising in transformed pulmonary neuroendocrine cells or a common progenitor shared with non-neuroendocrine lung epithelium, driven predominantly by tobacco-carcinogen-induced mutagenesis culminating in near-universal biallelic TP53 inactivation plus a second driver event (RB1 or STK11/KEAP1) (George et al., Nat Commun 2018, PMID:29535388). A minority of LCNECs arise via histologic transformation from EGFR-mutant lung adenocarcinoma under the selective pressure of EGFR-tyrosine-kinase-inhibitor therapy, driven mechanistically by biallelic RB1 loss (search synthesis of transdifferentiation literature; PNAS 2019 mouse-model paper, https://www.pnas.org/doi/10.1073/pnas.1821745116).

Risk Factors

Genetic/molecular risk factors (somatic, tumor-intrinsic; germline predisposition is not well established for sporadic LCNEC): - Biallelic TP53 inactivation — present in 64–92% of cases across cohorts (synthesis of PMID:33968782 review data). - Biallelic RB1 inactivation — 19–42% (concurrent with TP53 in "Type II/SCLC-like" tumors). - STK11/KEAP1 alterations — 17–33% (concurrent with TP53 in "Type I/NSCLC-like" tumors). - KRAS mutations — 4–24%. - NOTCH family gene alterations (inactivating) — 10–16%, implicated in loss of neuroendocrine differentiation control (George et al., PMID:29535388). - MYC family amplification (particularly MYCL, MYCN, MYC) has been implicated in driving transitions between neuroendocrine lineage states (ASCL1→NEUROD1 transition) that phenocopy LCNEC-like histology in SCLC models (Sci Adv 2020, https://www.science.org/doi/10.1126/sciadv.abc2578).

Environmental/behavioral risk factors: - Tobacco smoking is overwhelmingly the dominant risk factor: 92.8–98% of LCNEC patients have a smoking history, with many series reporting >40 pack-years in a majority of patients (PMC8162139; PMC9428409; PMC6532618). This mutagenic burden underlies the very high tumor mutational burden and TP53/STK11/KEAP1/KRAS mutation spectrum shared with squamous cell lung carcinoma and SCLC. - Age: median age at diagnosis ~65–66 years, skewing toward older adults (PMC8081906; PMID:33968782). - Sex: strong male predominance, consistent with the historical smoking-exposure skew, though the male:female gap has been narrowing in more recent cohorts as female smoking rates changed. - Prior EGFR-TKI exposure in EGFR-mutant adenocarcinoma is a specific, mechanistically defined risk pathway for acquired (transformed) LCNEC/SCLC.

Protective Factors

No established genetic or environmental protective factors specific to LCNEC have been robustly identified in the literature reviewed; smoking cessation reduces overall lung cancer risk generically but LCNEC-specific protective/modifier data are sparse.

Gene–Environment Interactions

The dominant gene–environment interaction is the tobacco-carcinogen mutational signature (SBS4-type, characterized by G>T transversions) converging on the TP53/RB1/STK11/KEAP1 tumor-suppressor network — i.e., chronic carcinogen exposure selects for and produces the specific biallelic tumor-suppressor loss-of-function events that define both LCNEC molecular subtypes. This is inferred from the near-universal smoking history combined with the mutational spectrum reported in comprehensive genomic profiling studies (George et al. PMID:29535388; Rekhtman et al., Clin Cancer Res 2016, "Genomic Profiling of Large-Cell Neuroendocrine Carcinoma of the Lung," https://aacrjournals.org/clincancerres/article/23/3/757/80338).

3. Phenotypes

Clinical signs/symptoms (respiratory, driven by anatomic location)

  • Centrally located tumors (a substantial minority, more than typical NSCLC adenocarcinoma but less central than SCLC): cough, hemoptysis, bronchial obstruction, post-obstructive/recurrent pneumonia.
  • Suggested HPO terms: Cough (HP:0012735), Hemoptysis (HP:0002105), Recurrent respiratory infections (HP:0002205).
  • Peripherally located tumors: frequently asymptomatic, identified incidentally on imaging — reflecting the tendency of LCNEC to present as a peripheral nodule/mass more often than SCLC.
  • Constitutional/systemic symptoms at presentation in advanced disease: weight loss, fatigue, dyspnea, chest pain.
  • HPO: Weight loss (HP:0001824), Fatigue (HP:0012378), Dyspnea (HP:0002094), Chest pain (not a canonical HPO term but codeable via SNOMED CT).

Paraneoplastic phenomena

LCNEC, sharing biology with SCLC, can produce paraneoplastic syndromes, though less commonly reported than in classic SCLC: - SIADH/hyponatremia (inappropriate ADH secretion) - Cushing syndrome (ectopic ACTH) - Lambert–Eaton myasthenic syndrome - Paraneoplastic neurological syndromes — peripheral neuropathy, limbic encephalitis, and case reports of opsoclonus-myoclonus syndrome as the presenting feature preceding LCNEC diagnosis (PMC10725307; AJRCCM abstract 2025). - Rare carcinoid-syndrome-like flushing/diarrhea has been described but is atypical for high-grade NEC. - Suggested HPO terms: Hyponatremia (HP:0002902), Cushingoid facies (HP:0000174), Myasthenia (HP:0003473), Peripheral neuropathy (HP:0009830), Encephalitis (HP:0002383).

Laboratory abnormalities

  • Elevated serum neuron-specific enolase (NSE) and pro-gastrin-releasing peptide (ProGRP) may be seen (SCLC-associated markers, less validated specifically for LCNEC).
  • Chromogranin A elevation in serum can occur but is neither sensitive nor specific.

Phenotype characteristics

  • Age of onset: predominantly adult/older-adult onset (median 65–66 years); pediatric/young-adult LCNEC is exceptionally rare (case reports exist, e.g., tarlatamab case report in a young adult, JTO Clin Res Rep).
  • Severity: uniformly high grade/aggressive by definition (WHO diagnostic criterion requires high mitotic count and often necrosis).
  • Progression: rapidly progressive; a majority of patients present with locoregionally advanced or metastatic (stage IV) disease — one large cohort reported 54.6% presenting at stage IV (synthesis, PMID:33968782).
  • Frequency among affected individuals: By definition, the histologic/molecular features described (necrosis, high Ki-67, TP53 alteration) are present in nearly all diagnosed cases since they constitute diagnostic criteria; paraneoplastic phenomena are comparatively uncommon (case-report level).

Quality of life impact

Given the aggressive course, poor prognosis (median OS 8–12 months in advanced disease; see Section 11), and frequent late-stage diagnosis, quality-of-life burden is substantial — encompassing respiratory symptom burden, treatment-related toxicity from platinum-etoposide chemotherapy or immunotherapy-related adverse events, and, in a subset, paraneoplastic neurological morbidity that can itself be disabling (e.g., the opsoclonus-myoclonus case series notes significant residual gait instability). Disease-specific QoL instrument data (e.g., EORTC QLQ-LC13) specific to LCNEC (as opposed to lung cancer broadly) were not identified in this search.

4. Genetic/Molecular Information

Causal/driver genes and prevalence (from integrative genomic cohorts)

Gene Alteration type Prevalence (pooled from Rekhtman 2016, George et al. 2018 [PMID:29535388], and subsequent reviews)
TP53 (HGNC:11998) Biallelic loss-of-function (missense, truncating, LOH) 64–92%
RB1 (HGNC:9884) Biallelic inactivation 19–42%
STK11 (HGNC:11389) Inactivating mutation 17–33%
KEAP1 (HGNC:6396) Inactivating mutation 19–31%
KRAS (HGNC:6407) Activating mutation (mutually near-exclusive w/ RB1 loss) 4–24%
NOTCH1/2/3/4 family Inactivating mutations 10–16%
MYC/MYCL/MYCN Amplification Reported in subsets, associated with lineage-state transitions

Molecular subtyping — Type I vs. Type II LCNEC

The landmark integrative genomic/transcriptomic study by George et al. (Nat Commun 2018, n=75 LCNEC, genomic n=60, transcriptomic n=69; PMID:29535388) defined two largely mutually exclusive molecular subgroups:

  • Type I LCNEC ("NSCLC-like"): biallelic TP53 + STK11/KEAP1 co-alteration (~37% of the discovery cohort, with other cohorts reporting 13–40%). Transcriptionally these tumors resemble SCLC/carcinoid neuroendocrine programs: ASCL1^high / DLL3^high / NOTCH^low.
  • Type II LCNEC ("SCLC-like"): biallelic TP53 + RB1 co-alteration (~35–42% of cohorts). These tumors show reduced neuroendocrine differentiation relative to SCLC, with a pattern of ASCL1^low / DLL3^low / NOTCH^high, and notably an upregulation of immune-related pathways — a potential biological basis for differential immunotherapy responsiveness.
  • Despite sharing individual genomic alterations with lung adenocarcinoma and squamous cell carcinoma, LCNEC forms its own distinct transcriptional cluster most similar to SCLC, not to NSCLC histologic subtypes — supporting the WHO reclassification of LCNEC as a neuroendocrine carcinoma rather than an NSCLC variant.
  • Follow-up real-world cohort data (PMID:33968782-linked synthesis) found substantial heterogeneity: in some series 52.7% of cases do not cleanly classify as either Type I or Type II, underscoring that this is a useful but imperfect binary framework, likely reflecting a spectrum/continuum of neuroendocrine differentiation states rather than two discrete classes.

Transcription-factor-based (SCLC-style) subtyping applied to LCNEC

Building on the four-subtype SCLC transcriptional classification (ASCL1, NEUROD1, POU2F3, YAP1), recent work has extended this framework to LCNEC: - A 2025 Nature Communications integrated molecular/clinical characterization of pulmonary LCNEC (https://www.nature.com/articles/s41467-025-63091-0) and companion analyses of NEUROD1/ASCL1/POU2F3/YAP1 expression signatures found that ~80% of LCNEC transcriptomes align with an SCLC-like transcriptional profile, predominantly ASCL1-driven or NEUROD1-driven with a smaller YAP1-high, low-neuroendocrine subgroup. - Prognostic implication: NE-high subtypes (especially NEUROD1-dominant) show the worst overall survival, whereas the YAP1-high subgroup — characterized by low neuroendocrine differentiation, elevated immune infiltration, and higher Rb protein expression — is associated with relatively better prognosis and potentially greater immunotherapy sensitivity. A cross-tissue five-transcription-factor classification framework for neuroendocrine carcinomas generally (Cancer Cell 2024, https://www.cell.com/cancer-cell/fulltext/S1535-6108(24)00163-6) situates LCNEC within this broader neuroendocrine-carcinoma taxonomy.

Variant classification and population frequency

Most driver alterations in LCNEC are somatic, not germline; population allele-frequency databases (gnomAD, ExAC) are not directly informative for a somatic-driver cancer, though tumor-suppressor loss-of-function variant classes (nonsense, frameshift, canonical splice-site, large deletion/LOH) predominate for TP53/RB1/STK11/KEAP1, consistent with a classical two-hit tumor-suppressor mechanism.

Functional consequences

  • TP53 loss-of-function abrogates DNA-damage checkpoint control and apoptosis, permitting genomic instability.
  • RB1 biallelic loss removes the G1/S checkpoint brake, permitting unrestrained proliferation and correlating with a more SCLC-like, highly proliferative, RB1-null, low-differentiation phenotype (consistent with dismech's general RB1/CDK4-6/E2F "evading growth suppressors" pattern).
  • STK11 (LKB1) loss deregulates AMPK/mTOR energy-sensing signaling and is separately associated (in NSCLC broadly) with impaired response to immune checkpoint blockade, a clinically important correlate carried into LCNEC Type I tumors.
  • KEAP1 loss constitutively activates NRF2 antioxidant signaling, promoting chemoresistance.

Chromosomal/epigenetic information

Comprehensive DNA methylation or chromatin-state datasets specific to LCNEC were not prominently returned in this search; the transcription-factor-driven lineage-state model (ASCL1/NEUROD1/POU2F3/YAP1) is understood to be substantially governed by chromatin-level lineage plasticity analogous to SCLC, but LCNEC-specific epigenomic (ENCODE/Roadmap-style) datasets are not yet a major established resource for this tumor type — noted here as a data gap.

5. Environmental Information

  • Tobacco smoke (the dominant environmental exposure) — see Section 2. Suggested exposure term: ECTO tobacco-smoke-exposure class terms (e.g., analogous to "exposure to cigarette smoke").
  • No specific occupational toxin, radiation, or pollution exposure was identified in the literature reviewed as an independent LCNEC risk factor beyond the generic lung-carcinogen literature (radon, asbestos) that applies to lung cancer broadly; LCNEC-specific epidemiologic case-control data isolating these factors were not found in this search.
  • Infectious agents: no established infectious/microbial etiology for pulmonary LCNEC. (Extrapulmonary neuroendocrine carcinomas at some sites, e.g., cervix, may co-occur with high-risk HPV infection as a contributing oncogenic driver at that anatomic site, analogous to the mechanism captured in the viral_oncogenesis module for HPV-driven cervical carcinoma, but this is a site-specific consideration for cervical LCNEC rather than a general LCNEC etiology.)

6. Mechanism / Pathophysiology

Cell of origin

LCNEC is believed to arise from pulmonary neuroendocrine cells (PNECs) or a shared basal/neuroendocrine progenitor, analogous to SCLC. Supporting evidence: expression of the master neuroendocrine transcription factor ASCL1 (achaete-scute homolog 1), normally restricted to PNECs, is retained in the neuroendocrine-high subset of LCNEC and SCLC, "indicating the neuroendocrine cell origin of these malignancies" (search synthesis). Suggested Cell Ontology term: pulmonary neuroendocrine cell (CL:0002251).

Mouse genetic models directly demonstrate that cell-of-origin determines tumor phenotype given an identical genetic lesion set: combined inactivation of Rb1, Rbl1 (p130), Pten, and Trp53 ("quadruple knockout") in all lung epithelial cell types (via Ad5-CMV-Cre) produces LCNEC, whereas the identical genetic inactivation restricted to basal cells (via Ad5-K5-Cre) produces SCLC instead (Ferone et al., PNAS 2020, https://www.pnas.org/doi/10.1073/pnas.1821745116). This is strong mechanistic (model-organism) evidence that LCNEC and SCLC are genetically overlapping but cell-of-origin-divergent neuroendocrine carcinomas — a key causal-chain insight: identical driver mutations (Rb1/Trp53/Pten loss) + differing epithelial cell-of-origin context → divergent histologic/molecular tumor phenotype (LCNEC vs. SCLC).

Molecular pathway cascade (causal chain)

  1. Chronic tobacco-carcinogen mutagenesis in bronchial/PNEC epithelium →
  2. Biallelic TP53 inactivation (near-universal, "gatekeeper" first hit) →
  3. Second-hit bifurcation into two convergent-but-distinct pathway states:
  4. RB1 co-loss → loss of G1/S checkpoint restraint → E2F-driven hyperproliferation, high neuroendocrine differentiation program suppression (ASCL1^low/DLL3^low), NOTCH pathway de-repression (NOTCH^high) → "Type II/SCLC-like" phenotype with high Ki-67 and immune-pathway upregulation.
  5. STK11/KEAP1 co-loss → AMPK/mTOR and NRF2 pathway dysregulation, retained ASCL1^high/DLL3^high neuroendocrine program, NOTCH^low → "Type I/NSCLC-like" phenotype.
  6. Downstream: loss of NOTCH-mediated lateral inhibition permits expansion of the neuroendocrine lineage program (paralleling the conserved Notch-controlled neuroendocrine-vs-non-neuroendocrine fate switch described generally for high-grade lung NECs).
  7. MYC-family (MYC/MYCL/MYCN) amplification can further drive lineage-state transitions (e.g., ASCL1-dominant → NEUROD1-dominant transcriptional states), which histologically and biologically manifest with LCNEC-like features even within an SCLC genomic background (Sci Adv 2020).
  8. Net result: unrestrained proliferation (high Ki-67, mean ~65.8%±20.8%), geographic tumor necrosis, and a highly aggressive, chemotherapy-initially-responsive but rapidly relapsing clinical phenotype.

Molecular functions / biological processes (suggested GO terms)

  • Negative regulation of cell cycle G1/S transition (RB1 loss → GO:0000082 positive regulation of G1/S transition, dysregulated)
  • DNA damage response / apoptotic signaling (TP53; GO:0006977, GO:0006915)
  • Notch signaling pathway (GO:0007219)
  • Regulation of neuroendocrine cell differentiation (GO:0071679-adjacent / achaete-scute lineage specification)
  • Cellular response to oxidative stress via NRF2/KEAP1 (GO:0034614, GO:1901031 — regulation of response to oxidative stress)
  • AMPK/mTOR signal transduction via STK11/LKB1 (GO:0032008 relevant analog)

Immune microenvironment

Type II (RB1-mutant) LCNEC shows upregulation of immune-related pathways transcriptionally, potentially correlating with the somewhat better observed responsiveness of RB1-altered/SCLC-like LCNEC to immune checkpoint blockade in some series, while STK11/KEAP1-altered (Type I) tumors — mirroring the well-established NSCLC finding — appear associated with poorer immunotherapy response (search synthesis of PMID:33968782-linked review).

Molecular profiling technologies applied

  • Transcriptomics: RNA-seq-based lineage subtyping (ASCL1/NEUROD1/POU2F3/YAP1) — see Section 4.
  • Genomics: targeted and whole-exome sequencing cohorts (George et al. PMID:29535388; Rekhtman et al. 2016).
  • Single-cell/spatial: not prominently represented in the literature surfaced by this search — a likely emerging area but not yet a mature LCNEC-specific resource base (data gap).
  • Functional genomics (CRISPR/DepMap): LCNEC-derived cell lines are represented within DepMap broadly as part of the neuroendocrine lung cancer cell line panel, but LCNEC-specific CRISPR screen publications were not surfaced in this search.

7. Anatomical Structures Affected

Organ level

  • Primary organ: lung (bronchus/lung parenchyma) is the prototypical and most-studied site — Uberon: lung (UBERON:0002048), bronchus (UBERON:0002185).
  • Extrapulmonary primary sites (each representing a distinct clinical entity under the same histologic/molecular umbrella): gastroenteropancreatic tract (esophagus, stomach, colon, rectum, pancreas), gynecologic tract (cervix, uterus/endometrium, ovary), genitourinary tract (bladder, prostate), breast, thymus, larynx/pharynx, paranasal sinus, and skin/other rare sites. Approximately 37% of extrapulmonary NECs occur in the gastroenteropancreatic tract, with the genitourinary and gynecologic tracts also well represented (PMC10743506).
  • Secondary/metastatic involvement: lung (contralateral/intrapulmonary), liver, bone, brain, and adrenal gland are common metastatic sites, mirroring SCLC's metastatic tropism. SEER-based analysis found single-organ metastasis in 26.0% and multi-organ metastasis in 14.8% of a cohort of 1,335 LCNEC patients, with lung and brain metastases each carrying a median OS of only 8 months (PMC8971719; PMC9773085).

Tissue/cell level

  • Neoplastic cell population: large epithelial cells with neuroendocrine morphology, derived from (or recapitulating) pulmonary neuroendocrine cells — CL:0002251 (pulmonary neuroendocrine cell) as the presumptive normal-cell analog.
  • Tumor architecture: organoid nesting, trabeculae, rosettes, palisading, with geographic necrosis.

Subcellular level

Neuroendocrine secretory-granule machinery is retained in tumor cells (basis for chromogranin A positivity, a dense-core-granule marker) — relevant GO Cellular Component: secretory granule (GO:0030141), specifically dense core granule (GO:0031045).

Localization

Approximately central vs. peripheral distribution is roughly split, with central tumors more often symptomatic (cough, hemoptysis, obstruction) and peripheral tumors more often incidental. No strong left/right or lobar lateralization pattern was identified in this search.

8. Temporal Development

  • Onset: adult-onset, typically 6th–7th decade of life (median ~65–66 years); pediatric and young-adult cases are rare outliers.
  • Onset pattern: often insidious for peripheral tumors (incidental imaging finding); can be more acute/subacute for centrally obstructing tumors (recurrent pneumonia, hemoptysis) or in cases presenting via paraneoplastic neurologic syndrome.
  • Staging: uses the standard AJCC/UICC TNM lung cancer staging system (same schema as NSCLC), unlike SCLC which is often staged with the older limited/extensive-stage system alongside TNM. A majority of patients (>50% in several cohorts) present at stage IV.
  • Progression rate: rapid; LCNEC's proliferative index (mean Ki-67 ~65.8%) situates it biologically between typical/atypical carcinoid (low-grade) and SCLC (very high-grade), but clinically it behaves aggressively, similar to SCLC.
  • Disease course pattern: generally progressive/relapsing rather than static; initial chemotherapy responses are often followed by relatively rapid relapse, paralleling the SCLC natural history.
  • Recurrence: common even after complete surgical resection in early-stage disease, motivating investigation of adjuvant chemotherapy (see Section 12).

9. Inheritance and Population

Epidemiology

  • Incidence: age-adjusted incidence of ~0.3 per 100,000 (0.4/100,000 in men, 0.3/100,000 in women), based on SEER 2000–2013 data; incidence appears to have been rising over time (from ~0.26 to 0.39 per 100,000 between 2004–2015 in one synthesis) — plausibly reflecting improved diagnostic recognition following the WHO reclassification as much as a true increase (PMC6441320; PMID:33968782-linked synthesis).
  • Proportion of lung cancers: LCNEC constitutes roughly 1–3% of all lung cancers, and pulmonary LCNEC accounts for 0.58% of all lung/bronchus carcinomas in one SEER-based accounting; it represents about 15% of all pulmonary neuroendocrine neoplasms.

Inheritance

LCNEC is predominantly a sporadic, somatically driven malignancy without an established Mendelian inheritance pattern (no OMIM entry for a monogenic LCNEC syndrome was identified). It is not classically associated with MEN1 or other hereditary neuroendocrine tumor syndromes the way well-differentiated NETs sometimes are, though the literature reviewed here did not surface data specifically excluding rare hereditary contributions in unusual young-onset cases.

Population demographics

  • Sex ratio: strong male predominance historically, tracking smoking-exposure demographics.
  • Age distribution: peaks in the 6th–7th decades; rare before age 40.
  • Geographic/ethnic variation: East Asian cohorts have been separately characterized genomically (Kang et al., PMID:33144445, "Genomic Profiling and Clinicopathological Characteristics of Neuroendocrine Tumors of the Lung in East Asian Patients"), suggesting some population-level genomic profiling differences exist, though a detailed comparative incidence/ethnicity breakdown was not fully resolved in this search.

10. Diagnostics

Histopathology and immunohistochemistry (the diagnostic cornerstone)

Diagnosis requires combined morphologic assessment plus immunohistochemical confirmation of neuroendocrine differentiation: - Neuroendocrine markers: chromogranin A (CgA), synaptophysin (Syn), and CD56/NCAM are typically diffusely positive; INSM1 and ASCL1 (hASH1) are emerging, high-sensitivity markers particularly useful in crush-artifact-limited small biopsy specimens (PathologyOutlines; PMID:33968782 synthesis). - Ki-67 proliferation index: characteristically high, mean ~65.8% (±20.8%) in one series, and is a key discriminator from carcinoid tumors (which have low Ki-67), especially valuable on small biopsies where architecture is hard to assess (PMC11404992). Higher Ki-67 within LCNEC itself has additional prognostic value. - TTF-1: variably positive; TTF-1/c-MYC co-expression phenotypes have been proposed as a stratification tool relevant to DLL3-targeted treatment selection (PMC8132912). - WHO recommends that a definitive LCNEC diagnosis, given tissue heterogeneity, be made preferentially on surgical resection specimens rather than small biopsies when possible, given sampling limitations.

Laboratory tests / biomarkers

  • Serum NSE, ProGRP, chromogranin A (adjunctive, non-diagnostic).

Imaging

  • [18F]-FDG PET/CT: LCNEC exhibits high glucose turnover due to poor differentiation and elevated GLUT1 expression, making FDG-PET well suited to staging, particularly nodal (N) staging, and superior to conventional CT in several validated series (EJNMMI Research, PMC8298649).
  • Somatostatin receptor imaging (¹¹¹In-pentetreotide/Octreoscan, newer ⁶⁸Ga-DOTATATE PET): more established for well-differentiated NETs; utility in high-grade LCNEC (which often has lower/variable SSTR2 expression than low-grade NETs) is comparatively limited, though it may aid staging in select SSTR-avid cases.

Genetic/genomic testing

  • Comprehensive genomic profiling (CGP) panels (NGS-based) are increasingly used both for diagnostic clarification (distinguishing LCNEC from poorly differentiated NSCLC or SCLC when morphology/IHC is ambiguous) and to inform Type I/Type II molecular subclassification with treatment implications (Lung Cancer journal, "Real-World Comprehensive Genomic Profiling Data for Diagnostic Clarity in Pulmonary LCNEC," https://www.lungcancerjournal.info/article/S0169-5002(23)00992-3/fulltext).
  • No standardized single-gene or hereditary-panel germline test is indicated given the sporadic somatic etiology.

Differential diagnosis

Poorly differentiated NSCLC (adenocarcinoma/squamous) lacking neuroendocrine markers; SCLC (smaller cell size, higher nuclear:cytoplasmic ratio, nuclear molding, absent nucleoli — key morphologic discriminators); atypical carcinoid (lower Ki-67, less necrosis).

Screening

No dedicated LCNEC-specific screening program exists; patients are typically captured within general low-dose CT lung cancer screening programs for high-risk smokers, though LCNEC-specific screening-detection yield data were not identified in this search.

11. Outcome/Prognosis

Survival statistics (population-based, SEER 2000–2013 cohort)

  • 5-year lung cancer-specific survival: 20.7–20.8%
  • 5-year overall survival: 16.7–16.8%
  • 3-year OS / cancer-specific survival: 22.8% / 26.5% (PMC6441320)
  • Median overall survival (all comers, mixed-stage): reported around 8–12 months in several syntheses; one large cohort reported median OS 9.7 months from diagnosis (PMID:33968782-linked synthesis).
  • Metastatic disease: median OS of only 8 months for patients with either lung-only or brain-only single-organ metastasis, with 1-year survival rates of 33% and 29% respectively (PMC8971719).

Treatment-outcome-stratified survival (advanced/metastatic disease)

  • Chemotherapy alone: median OS ~6.5 months.
  • Chemo-immunotherapy: median OS ~9.6 months (numerically longer, though not always statistically significant in smaller retrospective series) (ScienceDirect nationwide registry study).
  • First-line platinum doublet chemotherapy: median OS ~9.0 months.
  • Non-platinum chemotherapy: median OS ~4.0 months.
  • Immune checkpoint inhibitor-containing regimens (in one series): median OS as high as 26.4 months, though this likely reflects selection bias toward better-performance-status patients in retrospective cohorts rather than a robustly randomized-trial-confirmed effect size.

Prognostic factors

  • Stage at diagnosis (dominant driver of prognosis).
  • Molecular subtype: NEUROD1-dominant/high-neuroendocrine transcriptional subtype associated with worse OS; YAP1-high/low-neuroendocrine subtype associated with comparatively better prognosis (Nature Communications 2025 integrated characterization).
  • Ki-67 index: higher values associated with worse survival within the LCNEC category (PMC11404992).
  • Complete surgical resection in early-stage disease is associated with markedly better outcomes; complete resection rates of ~94% with 90-day postoperative mortality of ~7% have been reported in surgical series.
  • Adjuvant chemotherapy after complete resection, particularly with an SCLC-type regimen (platinum-etoposide) rather than an NSCLC-type regimen, is associated with improved survival in several retrospective series, though a randomized-trial-level evidence base is still lacking, and benefit appears more consistent in stage IIB than stage IIA disease (PMC7736707; Translational Cancer Research).

Complications

Brain metastasis is common and carries a particularly poor prognosis; other complications parallel those of aggressive lung malignancy generally (post-obstructive pneumonia, pleural effusion, superior vena cava syndrome in central tumors, paraneoplastic morbidity as above).

12. Treatment

First-line systemic therapy (advanced/metastatic disease)

  • Platinum–etoposide doublet chemotherapy has been the standard first-line regimen for metastatic LCNEC for over a decade, based on the phase II GFPC 0302 study, extrapolating the SCLC treatment paradigm given LCNEC's biological/clinical overlap with SCLC (synthesis from Frontiers Management of LCNEC, PMID:34513663). No significant OS difference has been found between platinum-etoposide and platinum-gemcitabine/taxane regimens in comparative retrospective analyses.
  • NCIT concept: Chemotherapy (NCIT:C15632); Pharmacotherapy (NCIT:C15986), with therapeutic_agent bound to cisplatin/carboplatin (platinum agents) and etoposide (CHEBI terms available for both).

Immunotherapy

  • Immune checkpoint inhibitors (anti-PD-1/PD-L1, alone or combined with chemotherapy) show promising activity, especially in Type II (RB1-altered, immune-pathway-upregulated) tumors.
  • DART (SWOG S1609) basket trial of combination nivolumab + ipilimumab (dual anti-PD-1/anti-CTLA-4 blockade) in the high-grade/non-pancreatic neuroendocrine carcinoma cohort reported an objective response rate of 44% in the high-grade neuroendocrine carcinoma subset specifically (vs. 0% ORR in low/intermediate-grade disease), and 25–26% ORR in the broader nonpancreatic/high-grade cohorts overall (Patel et al., PMID:31969335; companion high-grade NEN cohort report PMID:33882143). Dosing: ipilimumab 1 mg/kg IV every 6 weeks + nivolumab 240 mg IV every 2 weeks.
  • Ongoing prospective trials are testing atezolizumab + platinum/etoposide as first-line therapy specifically in advanced pulmonary LCNEC (NCT05470595), and pembrolizumab-based regimens in previously treated high-grade neuroendocrine carcinomas broadly.
  • STK11/KEAP1 co-mutated (Type I) tumors are, by analogy with the broader NSCLC literature, associated with relative immunotherapy resistance — a molecularly grounded rationale for future biomarker-stratified trial design.

Emerging/targeted therapy

  • DLL3-targeted therapy: DLL3 (Notch-ligand family) is expressed on the surface of a majority of SCLC cells and is also expressed in LCNEC (particularly the ASCL1^high/DLL3^high Type I subgroup), representing a tumor-restricted therapeutic target absent from normal tissue.
  • Rovalpituzumab tesirine (Rova-T), a DLL3-targeted antibody-drug conjugate, showed early promise in phase II but failed in phase III trials and was discontinued.
  • Tarlatamab, a DLL3×CD3 bispecific T-cell engager, achieved a 55% objective response rate and median PFS of 4.9 months in the phase 2 DeLLphi-301 trial (in SCLC); case reports document partial responses in LCNEC as well, including in a young-adult patient (JTO Clin Res Rep; PMC11986208). Cytokine release syndrome is a recognized, generally manageable toxicity.
  • NCIT/therapeutic-modality mapping: therapeutic_modality: ANTISENSE_OLIGONUCLEOTIDE does not apply here — tarlatamab and Rova-T fall under MONOCLONAL_ANTIBODY/bispecific-engager and antibody-drug-conjugate categories respectively (best captured as MONOCLONAL_ANTIBODY or OTHER pending a dedicated bispecific-T-cell-engager modality value).

Surgery

  • Surgical resection with curative intent is the treatment of choice for early-stage (resectable) LCNEC, given the tumor's biological ambiguity and the general principle that localized high-grade lung tumors benefit from resection when feasible (EJNMMI Research). NCIT: Surgical Procedure (NCIT:C15329).

Radiation

  • Radiotherapy is used in the definitive, adjuvant, and palliative settings, including for brain metastasis management (whole-brain RT or stereotactic radiosurgery, by analogy with SCLC brain-metastasis management, though LCNEC-specific prophylactic cranial irradiation data are not well established).

Combination/sequential strategies

  • Endostar (an anti-angiogenic agent) plus pembrolizumab combined with platinum-doublet chemotherapy has been reported in case-report form as a novel first-line approach for advanced pulmonary LCNEC (PMC9202532).
  • Cabozantinib + nivolumab + ipilimumab is under investigation for poorly differentiated neuroendocrine tumors broadly (NCT04079712).

Treatment for extrapulmonary LCNEC

Platinum-based chemotherapy (mirroring SCLC/pulmonary LCNEC management) remains the standard-of-care backbone for extrapulmonary neuroendocrine carcinomas of any primary site, with further site-specific and biomarker-driven approaches under active investigation (PMC10743506).

13. Prevention

No LCNEC-specific primary, secondary, or tertiary prevention program was identified in the literature reviewed. Given the overwhelming (92–98%) association with tobacco smoking, primary prevention via smoking cessation and tobacco control is the principal actionable prevention lever, consistent with lung cancer prevention broadly (CDC/WHO tobacco control frameworks). Secondary prevention (early detection) relies on inclusion within standard low-dose CT lung cancer screening programs for eligible high-risk smokers, though LCNEC-specific screening sensitivity/yield data were not found. No LCNEC-specific vaccine, chemoprophylaxis, or genetic/carrier screening program exists, consistent with its sporadic somatic (non-hereditary) etiology.

14. Other Species / Natural Disease

Naturally occurring LCNEC as a distinct veterinary clinical entity is not well documented in the literature surfaced by this search; pulmonary neuroendocrine tumors are reported in veterinary oncology literature more generally, but a dedicated OMIA (Online Mendelian Inheritance in Animals) entry or veterinary case-series literature specific to "large cell neuroendocrine carcinoma" was not identified — noted here as a data gap rather than a confirmed absence.

15. Model Organisms

Genetically engineered mouse models (GEMMs)

The most directly relevant and well-characterized model system is the quadruple-knockout (QKO) mouse: conditional inactivation of Rb1, Rbl1 (p130), Pten, and Trp53 in lung epithelium. - Cre-driver-dependent phenotype divergence (Ferone et al., PNAS 2020, https://www.pnas.org/doi/10.1073/pnas.1821745116): - Ad5-CMV-Cre (targets all lung epithelial cell types) → large-cell neuroendocrine carcinoma. - Ad5-K5-Cre (targets basal cells specifically) → small-cell lung carcinoma. - This model directly demonstrates cell-of-origin as a determinant of neuroendocrine lung cancer histologic subtype given an identical combinatorial genetic lesion (Rb1/Rbl1/Pten/Trp53 loss), closely recapitulating the human TP53/RB1 co-mutation signature that defines "Type II/SCLC-like" LCNEC. - Phenotype recapitulation: the model produces "high-grade malignant neuroendocrine lung carcinomas strikingly similar to human disease," supporting high translational fidelity for the RB1/TP53-co-mutant molecular subtype specifically; it is less directly informative for the STK11/KEAP1-mutant ("Type I") molecular subtype, which would require a distinct genetic-lesion combination not centered on Rb1 loss. - Trp53 mutant-specific models: Trp53 point-mutant (rather than null) alleles have been shown to drive neuroendocrine lung cancer through a combination of loss-of-function and gain-of-function mechanisms, the latter specifically affecting chemotherapy response (Sotillo et al., Mol Cancer Ther 2017, PMID: available via https://pmc.ncbi.nlm.nih.gov/articles/PMC5716875/), offering a model for studying platinum-etoposide chemoresistance mechanisms.

Other model systems

  • Patient-derived cell lines/xenografts (PDX): referenced in genomic-profiling and DLL3/tarlatamab preclinical literature but not exhaustively catalogued in this search; LCNEC-specific cell lines exist within broader neuroendocrine lung cancer cell line resources (e.g., within DepMap/Cellosaurus), though a dedicated LCNEC PDX registry akin to CCLE/DepMap-style comprehensive catalogs was not surfaced.
  • EGFR-mutant transformation models: mouse and cell-line models of EGFR-TKI-resistant transdifferentiation from adenocarcinoma to SCLC/LCNEC, centered on Rb1 biallelic inactivation, are used to study the acquired-resistance mechanistic pathway (search synthesis referencing PNAS 2020 and related EGFR-transdifferentiation literature).

Applications and limitations

These GEMMs are principally used to study: (1) the causal sufficiency of the TP53/RB1/Pten tumor-suppressor combination for high-grade neuroendocrine lung carcinoma, (2) the cell-of-origin determinant of LCNEC-vs-SCLC histologic fate, and (3) chemotherapy-response mechanisms tied to specific Trp53 mutant alleles. A key limitation is that no widely used GEMM directly models the STK11/KEAP1-driven "Type I" molecular subtype of human LCNEC, representing a translational gap for roughly a third of human cases.

Summary of Key Ontology-Term Suggestions

Domain Suggested term(s)
Disease MONDO (large cell neuroendocrine carcinoma, organ-specific children); ICD-O-3 8013/3
Causal genes HGNC:11998 (TP53), HGNC:9884 (RB1), HGNC:11389 (STK11), HGNC:6396 (KEAP1), HGNC:6407 (KRAS)
Cell of origin CL:0002251 (pulmonary neuroendocrine cell)
Anatomy UBERON:0002048 (lung), UBERON:0002185 (bronchus)
Key phenotypes HP:0012735 (Cough), HP:0002105 (Hemoptysis), HP:0002902 (Hyponatremia), HP:0000174 (Cushingoid facies), HP:0003473 (Myasthenia), HP:0002383 (Encephalitis), HP:0001824 (Weight loss)
Biological processes GO:0007219 (Notch signaling pathway), GO:0006977 (DNA damage response, p53 mediator), GO:1901031 (regulation of response to oxidative stress)
Treatments NCIT:C15632 (Chemotherapy), NCIT:C15986 (Pharmacotherapy), NCIT:C15329 (Surgical Procedure), NCIT:C15313 (Radiation Therapy)

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Large Cell Neuroendocrine Carcinoma (LCNEC): A Comprehensive Disease Characteristics Report
openscientist-autonomous 49 citations 2026-08-20T04:15:54.844572

Large Cell Neuroendocrine Carcinoma (LCNEC): A Comprehensive Disease Characteristics Report

Category: Neoplastic | Primary MONDO ID: MONDO:0005057 (site-agnostic) / MONDO:0003960 (pulmonary) | ICD-O: 8013/3 | NCIT: C4118

Summary

Large cell neuroendocrine carcinoma (LCNEC) is a rare, high-grade, poorly differentiated neuroendocrine carcinoma that accounts for approximately 0.3–3% of all lung cancers and also arises at extrapulmonary sites (thymus/mediastinum, gastrointestinal tract, uterus/cervix, breast, gallbladder, ovary). It is a tobacco-driven somatic malignancy of predominantly elderly male smokers. Diagnosis rests on non-small-cell neuroendocrine morphology — large cells, high mitotic rate (>10 mitoses/2 mm², typically ~70–75 mean), extensive necrosis, and organoid/palisading architecture — combined with mandatory immunohistochemical confirmation of neuroendocrine differentiation (chromogranin A, synaptophysin, CD56, with INSM1 and Ki-67 as adjuncts). Central pathology review reveals substantial interobserver variability, with LCNEC confirmed in only ~67% of submitted cases in one national registry, underscoring that this remains a diagnostically challenging entity.

Molecularly, LCNEC occupies a biological space that bridges small cell lung cancer (SCLC) and non-small cell lung cancer (NSCLC). Near-universal TP53 alteration coexists with two dominant genomic subtypes: an SCLC-like subtype (RB1 + TP53 co-alteration) and an NSCLC-like subtype (KEAP1, KRAS, STK11, SMARCA4, CDKN2A/B). A third carcinoid-like group (MEN1 mutation without TP53) is recognized in large comprehensive genomic profiling cohorts. Orthogonal transcription-factor and YAP1-based classifications further subdivide the disease into therapeutically distinct subsets (ASCL1/NEUROD1-driven, DLL3-high, immune-cold vs. YAP1-high, mesenchymal, inflamed). Tumor mutational burden is high (~12.7 mut/Mb), and homologous-recombination pathway defects, NOTCH-pathway alterations, and epigenetic dysregulation (DNMT1/DNMT3A upregulation, promoter hypermethylation, ASCL1 super-enhancers) contribute to pathogenesis. LCNEC can also arise via neuroendocrine transformation of EGFR-mutant lung adenocarcinoma as an acquired resistance mechanism, driven by MYC amplification atop shared clonal TP53/STK11 mutations.

Prognosis is poor overall — stage IV median overall survival (OS) is approximately 7.4 months — although early-stage resected disease reaches 53–86% 5-year survival. Treatment is largely extrapolated from SCLC and NSCLC: platinum-etoposide chemotherapy remains the first-line backbone, chemoimmunotherapy improves outcomes in advanced disease (pooled ORR 49%, first-line OS HR 0.72), surgery is central to localized disease, and DLL3-directed bispecific T-cell engager therapy (tarlatamab) is an emerging targeted option supported by early clinical activity in LCNEC and DLL3-high pulmonary carcinoid.

1. Disease Information

Overview. LCNEC is a poorly differentiated, high-grade neuroendocrine carcinoma composed of large cells with neuroendocrine morphology (organoid nesting, palisading, rosette-like structures, trabeculae) and confirmed neuroendocrine differentiation. In the WHO framework, lung neuroendocrine neoplasms are divided into well-differentiated typical/atypical carcinoids and poorly differentiated high-grade carcinomas comprising LCNEC and SCLC (PMID: 39756451; PMID: 28871510).

Key identifiers.

Resource Identifier
MONDO (site-agnostic) MONDO:0005057 — large cell neuroendocrine carcinoma
MONDO (pulmonary) MONDO:0003960 — pulmonary large cell neuroendocrine carcinoma
MONDO (lung combined LCNEC) MONDO:0004142
MONDO (parent NEC) MONDO:0002120 — neuroendocrine carcinoma
MONDO (lung NE neoplasm) MONDO:0005454
MONDO (thymic) MONDO:0003047
MONDO (ovarian) MONDO:0003049
MONDO (breast) MONDO:0003959
MONDO (pancreatic) MONDO:0006347
MONDO (cervical) MONDO:0006138
ICD-O morphology 8013/3
NCIT C4118 (Lung Large Cell Neuroendocrine Carcinoma)
MeSH D018278 (Carcinoma, Neuroendocrine)
OMIM None — somatic malignancy, no Mendelian entry

These identifiers were verified via EBI OLS4 MONDO lookup (2026-08) and are documented in F014/F015 (PMID: 42526975; PMID: 39756451).

Synonyms / alternative names. Pulmonary large cell neuroendocrine carcinoma (PLCNEC); large-cell neuroendocrine carcinoma of the lung; high-grade neuroendocrine carcinoma, large cell type; combined LCNEC (when admixed with adenocarcinoma, squamous cell carcinoma, or other NSCLC components).

Source of information. Content is derived from aggregated disease-level resources — WHO Classification of Tumours, national registries (SEER, Netherlands Cancer Registry, French EPITHOR), comprehensive genomic profiling cohorts, and the primary literature — rather than individual EHR records.

2. Etiology

Causal factors. LCNEC is a somatic, tobacco-driven malignancy. There is no Mendelian/germline cause; disease arises through accumulation of somatic mutations, near-universally including TP53 alteration, in the setting of heavy tobacco exposure (PMID: 36304941; F002, F006).

Environmental / lifestyle risk factors. - Tobacco smoking is the dominant risk factor: "Most of the LCNEC patients are elderly smoking male" (PMID: 36304941). Tobacco consumption is independently associated with OS in resected disease (PMID: 42341696). - Age and male sex — patients are typically elderly (mean age at surgery ~63.8 years) and male (~68.8%) (PMID: 42341696). - Cannabis smoking — associated with earlier age at lung cancer diagnosis and a higher relative frequency of LCNEC and adenocarcinoma histology among cannabis vs. tobacco-only smokers, though not an independent prognostic factor (PMID: 40393352).

Genetic risk factors. No established germline susceptibility loci. The relevant genetic events are somatic drivers (see Section 4). Homologous-recombination pathway alterations are present in a subset and are prognostically relevant (PMID: 35641209).

Protective factors. No validated genetic or environmental protective factors are established for LCNEC specifically. By analogy to lung cancer generally, smoking cessation is the principal modifiable protective behavior.

Gene–environment interactions. Tobacco carcinogen exposure drives the high mutational burden (TMB ~12.7 mut/Mb) and the TP53/RB1 and NSCLC-driver mutation spectrum that defines LCNEC subtypes (PMID: 35641209; PMID: 40830141).

3. Phenotypes

Clinical manifestations are non-specific. LCNEC is often peripheral and in the upper lobes (PMID: 36304941).

Phenotype Type HPO suggestion Characteristics
Cough Symptom HP:0012735 Adult/geriatric onset; non-specific
Dyspnea Symptom HP:0002094 Progressive with tumor burden
Hemoptysis Sign HP:0002105 Variable
Chest pain Symptom HP:0100749 Variable
Weight loss / cachexia Constitutional HP:0001824 Advanced disease
Pulmonary neoplasm Physical HP:0100526 Frequently peripheral, upper lobe
Bone metastasis Complication HP:0000766 (abnormal bone) ~23% synchronous at diagnosis in high-grade lung NEC (PMID: 40634407)
Brain metastasis Complication HP:0002060 (CNS neoplasm) Independent adverse prognostic factor (PMID: 39268117)
Liver metastasis Complication HP:0006554 Independent adverse prognostic factor (PMID: 39268117)

Onset / severity / progression. Adult-to-geriatric onset; severe and rapidly progressive. "The clinical manifestations are not specific," which contributes to late-stage presentation (PMID: 36304941). Nearly half of patients present at advanced stage (PMID: 39287289). Unlike well-differentiated carcinoids, functional hormonal (carcinoid) syndromes are uncommon.

Quality-of-life impact. Direct EQ-5D/SF-36 LCNEC data were not identified; by extrapolation from high-grade lung cancer, symptom burden (dyspnea, pain from metastases, fatigue) and treatment toxicity substantially impair daily functioning. This is a knowledge gap.

4. Genetic / Molecular Information

Causal / driver genes and subtypes (F001, F004, F006). LCNEC has two dominant genomic subtypes plus a carcinoid-like minority:

Subtype Defining alterations Frequency / evidence
SCLC-like RB1 + TP53 co-alteration n=557 in CGP cohort (PMID: 38159439); ~80% align with SCLC transcriptional profile (PMID: 40830141)
NSCLC-like KEAP1, KRAS, STK11, SMARCA4, CDKN2A/B, MTAP, CCND1, FGF3/4/19 (PMID: 40830141; PMID: 38159439)
Carcinoid-like MEN1 mutation without TP53 GA n=25 (PMID: 38159439)

"Genomic analysis identifies distinct non-small cell lung cancer-like (NSCLC-like, KEAP1, KRAS, STK11 mutations) and SCLC-like (RB1, TP53 mutations) LCNEC subtypes, with 80% aligning with SCLC transcriptional profiles." (PMID: 40830141)

Additional recurrently altered genes. NOTCH1, NOTCH2, PRKDC, SPTA1, PTPRD are mutated at higher rates in LCNEC/SCLC than in carcinoids (PMID: 35641209). 26.3% of LCNECs harbor classical NSCLC driver-gene alterations. The NSCLC-like program also involves PI3K/AKT and RAS/MAPK genes (PIK3CA, KRAS, STK11, KEAP1).

Variant classification, type, and origin. Alterations are somatic (not germline). Types include truncating/nonsense and missense mutations (TP53, STK11), loss-of-function deletions (RB1, CDKN2A/B, SMARCA4), and copy-number events (MYC amplification during transformation; FGF3/4/19, CCND1 amplification). TP53 and RB1 loss are loss-of-function tumor-suppressor events; KRAS is gain-of-function. Somatic origin is confirmed by COSMIC/TCGA-type profiling; there are no ClinVar germline pathogenic entries defining this disease.

Tumor mutational burden. High: "Large cell neuroendocrine carcinoma (12.7 mutations/Mb) and SCLC (11.9 mutations/Mb) showed higher tumor mutational burdens than TC (2.4 mutations/Mb) and AC (7.1 mutations/Mb)" (PMID: 35641209).

Transcription-factor / YAP1 axes (F004). YAP1 status defines two intrinsic subtypes (PMID: 39150543): - YAP1-high: mesenchymal, inflamed; co-alterations in CDKN2A/B and SMARCA4 alongside TP53; vulnerable to MEK- and AXL-targeting. - YAP1-low: epithelial, immune-cold; TP53+RB1 co-mutation; expresses SCLC transcription factors ASCL1 and NEUROD1; DLL3/CD56 targeting vulnerability.

Modifier genes. Homologous-recombination pathway alterations act as therapeutic-response modifiers, predicting longer PFS on systemic therapy (P=.005) (PMID: 35641209).

Epigenetic information (F011). First study of DNMT expression in LCNEC (18 cases) found "upregulation of both DNMT1 and DNMT3A compared to control normal lung tissue" (PMID: 41854102). Promoter hypermethylation of tumor suppressors (e.g., RASSF1, CDKN2A, APC, BRCA1, CDH1, MGMT, RARβ, RUNX3, TIMP3) links LCNEC to both NSCLC and SCLC — "LCNEC may serve as a biological bridge between non-small cell and small-cell lung carcinoma" (PMID: 39832203). ASCL1 acts as a master transcriptional regulator associated with super-enhancers (PMID: 30121393).

Chromosomal abnormalities. Chromosomal instability, MYC amplification (especially during neuroendocrine transformation), and copy-number alterations at FGF/CCND1 loci. MSI occurs in ~10% of gastric/colorectal NEC but is uncommon in pulmonary LCNEC.

5. Environmental Information

  • Environmental factors: Tobacco smoke carcinogens are the principal environmental driver; ionizing radiation and other inhaled carcinogens are plausible by analogy to high-grade lung cancers.
  • Lifestyle factors: Cigarette smoking (dominant) and cannabis smoking (associated with earlier onset and higher relative LCNEC frequency; PMID: 40393352).
  • Infectious agents: Not applicable for pulmonary LCNEC. However, HPV (particularly HPV18) is causally associated with cervical large cell neuroendocrine carcinoma (PMID: 42521492; PMID: 42351440). Merkel cell polyomavirus causes cutaneous Merkel cell carcinoma, a related high-grade NEC used as a comparator in the literature.

6. Mechanism / Pathophysiology

Causal chain (upstream → downstream).

Tobacco carcinogen exposure
│  (high mutational load, TMB ~12.7/Mb)
▼
TP53 loss  ──►  genomic instability / checkpoint failure
│
   ┌────┴─────────────────────────┐
   ▼                              ▼
RB1 loss (SCLC-like)        KEAP1/KRAS/STK11/SMARCA4 (NSCLC-like)
   │  NOTCH low, ASCL1/NEUROD1     │  RAS/MAPK, PI3K/AKT, KEAP1-NRF2
   │  DLL3 high, immune-cold       │  YAP1-high, mesenchymal, inflamed
   ▼                              ▼
Neuroendocrine differentiation   Epithelial/mesenchymal program
   │                              │
   └──────────┬───────────────────┘
      ▼
   High-grade proliferation (Ki-67 high, >10 mitoses/2mm²),
   necrosis, spread-through-air-spaces (STAS 71–88%)
      ▼
   Early nodal/distant metastasis (bone ~23%, brain, liver) → poor survival

Molecular pathways. RAS/MAPK, PI3K/AKT/mTOR, NOTCH signaling, KEAP1–NRF2 (via KEAP1 mutation), Hippo/YAP1, and cell-cycle control (RB1–cyclin D1/CDKN2A) (PMID: 35641209; PMID: 39150543; PMID: 40830141). Suggested GO terms: GO:0007219 (Notch signaling pathway), GO:0007265 (Ras protein signal transduction), GO:0035329 (Hippo signaling), GO:0007049 (cell cycle).

Cellular processes. Cell-cycle dysregulation (RB1/CDKN2A loss), impaired apoptosis (TP53 loss), neuroendocrine lineage plasticity, and chromosomal instability. Suggested GO terms: GO:0006915 (apoptotic process), GO:0051301 (cell division), GO:0030154 (cell differentiation).

Protein dysfunction. Loss-of-function of p53 and RB1 tumor suppressors; SMARCA4 (BRG1) inactivation destabilizes the SWI/SNF chromatin-remodeling complex; gain-of-function KRAS. UniProt: TP53 (P04637), RB1 (P06400), SMARCA4 (P51532), KRAS (P01116), ASCL1 (P50553), DLL3 (Q9NYJ7).

Metabolic changes. L-type amino-acid transporter 1 (LAT1/SLC7A5) is overexpressed in 52.4% of LCNEC and correlates with Ki-67, nodal metastasis, and poor outcome (PMID: 18440724) — reflecting elevated amino-acid demand of proliferating tumor cells.

Immune involvement (F010). Modestly immunogenic relative to SCLC. PD-L1 on tumor cells ~15.1%; immune-cell infiltration and PD-L1-on-immune-cells more strongly correlate with LCNEC than SCLC (57.6% vs 23.3%; 45.8% vs 22.5%; both p<0.01), correlating with high nonsynonymous mutation burden (PMID: 29378266). PTEN loss occurs in ~9.5%. However, ASCL1-high/YAP1-low tumors are immune-cold, and some extrapulmonary variants (HPV18+ cervical LCNEC) are poorly immunogenic (TMB 1.21/Mb, minimal PD-L1) with ICI resistance (PMID: 42521492).

Tissue damage mechanisms. Extensive tumor necrosis, spread-through-air-spaces (STAS identified in 71–88% of high-grade large-/small-cell NE carcinomas; PMID: 31201506), and destructive local/metastatic growth.

Cell types. Pulmonary neuroendocrine cells / their precursors are the presumed cell of origin; adenocarcinoma cells can transdifferentiate into LCNEC (see transformation, below). Suggested CL terms: CL:0000165 (neuroendocrine cell), CL:0002333 (pulmonary neuroendocrine cell), CL:0001063 (neoplastic cell).

Multi-omics / transformation (F013). Combined LCNEC-adenocarcinoma cases show shared clonal TP53 and STK11 mutations across components with MYC amplification acquired during neuroendocrine transformation (PMID: 39868963). Histologic transformation to LCNEC is an acquired EGFR-TKI resistance mechanism in EGFR-mutant adenocarcinoma (PMID: 28768973).

7. Anatomical Structures Affected

Organ level. Primary organ is most commonly the lung (~85% of LCNEC; UBERON:0002048), typically peripheral and upper-lobe. Extrapulmonary primaries (F007): thymus/mediastinum (UBERON:0002370), gastrointestinal tract — large-cell NEC was 42% of GI-NECs in a 143-case cohort (PMID: 36264285), uterus/cervix (UBERON:0000995/UBERON:0000002; PMID: 42111278), breast (UBERON:0000310; PMID: 39585672), gallbladder (UBERON:0002110; PMID: 40789532), and ovary (UBERON:0000992).

Secondary organ involvement. Bone (~23% synchronous), brain, liver, and regional lymph nodes are common metastatic sites and independent adverse prognostic factors (PMID: 39268117; PMID: 40634407).

Body systems. Respiratory (primary), plus skeletal, nervous (CNS), hepatic, and lymphatic systems (metastatic).

Tissue and cell level. Epithelial-derived neuroendocrine tumor; targeted/derived cell type is the neuroendocrine cell (CL:0000165) and pulmonary neuroendocrine cell (CL:0002333).

Subcellular level. Dense-core neurosecretory granules (basis of chromogranin A/synaptophysin positivity). Suggested GO cellular-component terms: GO:0030141 (secretory granule), GO:0005739 (mitochondrion), GO:0005634 (nucleus).

Localization / lateralization. Pulmonary LCNEC is typically a solitary peripheral mass, often upper lobe; laterality is variable (unilateral primary with potential bilateral/distant metastases).

8. Temporal Development

Onset. Adult/geriatric (mean age at surgery ~63.8 years; PMID: 42341696). Onset is insidious with non-specific symptoms, frequently leading to advanced-stage presentation (PMID: 36304941; PMID: 39287289).

Progression / staging. Staged by AJCC TNM (lung). Progression is rapid, with early nodal and distant metastasis; ~half present at advanced stage and ~23% of high-grade lung NEC have synchronous bone metastasis at diagnosis (PMID: 40634407). Disease course is aggressive and progressive rather than relapsing-remitting.

Duration / patterns. Chronic in the sense of a lethal, progressive course; median OS in stage IV is ~7.4 months (PMID: 41240593). Remissions are treatment-induced, generally not durable. The critical intervention window is at the localized/resectable stage, where surgery offers the best survival.

9. Inheritance and Population

Epidemiology. Incidence ~0.3–3% of lung cancers (PMID: 36304941); ~3% is a commonly cited figure (PMID: 41510101). Incidence appears to be rising, partly due to improved diagnostics (PMID: 40114491).

Inheritance. Not heritable — somatic, tobacco-driven malignancy with no Mendelian OMIM entry (F014). Concepts of penetrance, expressivity, anticipation, founder effects, consanguinity, and carrier frequency are not applicable.

Demographics. Male predominance (~68.8% men; PMID: 42341696); elderly smokers. Sex is an independent prognostic factor (DSS HR ~1.17 for the higher-risk sex; PMID: 39268117). Geographic distribution parallels tobacco-use patterns; no established ethnic predisposition beyond smoking prevalence.

10. Diagnostics

Histopathology + IHC (mandatory). Diagnosis requires non-small-cell neuroendocrine morphology (large cells, organoid/palisading architecture, extensive necrosis, severe atypia, >10 mitoses/2 mm² [typically mean ~70–75]) plus IHC confirmation of neuroendocrine differentiation. "The confirmation of the neuroendocrine signature by immunohistochemistry is mandatory for the diagnosis; a minimum panel comprising chromogranin A and synaptophysin is recommended" (PMID: 28871510). CD56 is diffusely positive; INSM1 and high Ki-67 aid diagnosis (PMID: 36304941; PMID: 40805240).

Ki-67 / grading. Grading in lung NE neoplasms uses mitotic count ±necrosis; Ki-67 is a helpful adjunct (and its formal inclusion is debated; PMID: 38728050). LCNEC shows a high Ki-67 index.

Diagnostic reliability. Substantial interobserver variability; central pathology review confirmed LCNEC in only 67% of submitted cases in the Netherlands Cancer Registry (others reclassified as SCLC 34%, NSCLC-NOS 34%) (PMID: 41240593). A systematic review found central pathology review is applied in <one-third of studies with marked methodological heterogeneity (PMID: 42556470).

Molecular / genomic testing. Comprehensive genomic profiling (NGS panels, WES) is useful for subtyping (SCLC-like vs NSCLC-like vs carcinoid-like) and for identifying actionable alterations (PMID: 38159439; PMID: 41653583). RB1 IHC (pRb status) is used for stratification in registry studies (PMID: 41240593). Emerging epigenomic cfDNA/liquid-biopsy approaches can detect neuroendocrine transformation noninvasively (PMID: 38912901).

Imaging. CT and PET for staging; brain MRI given CNS metastasis risk; pro-gastrin-releasing peptide (pro-GRP) can serve as a circulating tumor marker in NE tumors and tracks response (e.g., 1610 → 49.7 ng/mL on tarlatamab; PMID: 42491047).

Differential diagnosis. SCLC (smaller cells, finer chromatin, higher N:C ratio), basaloid squamous carcinoma, atypical carcinoid (lower mitoses, no necrosis), and metastatic NEC from other sites. IHC (INSM1, chromogranin, synaptophysin, TTF-1, Ki-67) and molecular context resolve most cases.

11. Outcome / Prognosis

Survival. Poor overall; stage-dependent.

Setting Outcome Source
Stage IV, panel-reviewed Median OS ~7.4 months PMID: 41240593
Resected (EPITHOR, n=1,229) 5-year OS 52.9% (vs SCLC 45.5%) PMID: 42341696
Resected, stage-selected series 5-year survival ~86% PMID: 41376913

Independent prognostic factors (SEER, n=2,897; F008). Surgery (HR 0.481, protective), chemotherapy (HR 0.450, protective), bone metastasis (HR 1.284), brain metastasis (HR 1.167), liver metastasis (HR 1.223), plus AJCC N-stage, tumor stage, sex, and age (PMID: 39268117). Tobacco, sex, TNM stage, and histologic type were independently associated with OS in EPITHOR (PMID: 42341696).

Molecular prognostic markers. Homologous-recombination pathway alterations predict longer PFS with systemic therapy (P=.005; PMID: 35641209); LAT1 overexpression predicts poor outcome (PMID: 18440724); immune-cell infiltration associates with better PFS (PMID: 29378266).

Complications. Bone, brain, and liver metastases; early death is common in stage IV (predictive nomograms achieve AUC ~0.85; PMID: 39287289).

12. Treatment

Treatment is extrapolated from SCLC and NSCLC. Suggested NCIT terms in parentheses.

Pharmacotherapy — first line. Platinum (cisplatin/carboplatin) + etoposide chemotherapy is the backbone: "In metastatic disease, etoposide-platinum chemotherapy remains the first-line treatment, while targeted therapy can be considered if tumors harbor actionable genomic alterations" (PMID: 41653583). NCIT: C63419 (etoposide), C376 (cisplatin), C1282 (carboplatin).

Chemoimmunotherapy (F003). Adding immune checkpoint inhibitors improves outcomes: pooled ORR 49% (95% CI 43–55); vs chemo alone ORR OR 2.52; first-line chemo+ICI improved OS (HR 0.72, 95% CI 0.58–0.89) without increasing grade ≥3 AEs (PMID: 42208366). Real-world registry data show a survival benefit of immunotherapy (median OS 10.7 vs 6.7 months; HR 0.53) although panel-reviewed cohorts show a smaller, non-significant effect (PMID: 41240593). The phase II FIRST-NEC trial (durvalumab + platinum-etoposide, NCT06393816) is prospectively evaluating first-line immunochemotherapy (PMID: 42526918). NCIT: C1649 (pembrolizumab), checkpoint inhibitors (durvalumab).

Targeted / emerging — DLL3-directed therapy (F009). DLL3 is highly expressed in SCLC-like/ASCL1-associated LCNEC. Tarlatamab (DLL3×CD3 bispecific T-cell engager) received FDA accelerated approval (2024) and full approval (2025) for SCLC (PMID: 42449715). In a relapsed/refractory LCNEC case (6th-line), tarlatamab produced a partial response (130→78 mm, 40% reduction) with pro-GRP falling 1610→49.7 ng/mL and only grade 1 CRS (PMID: 42491047). In DLL3-high pulmonary carcinoid (n=11), response rate was 73% with 100% disease control (PMID: 42562260). Additional emerging modalities: TROP2- and B7-H3-directed agents and antibody-drug conjugates (PMID: 42592685; PMID: 42582332). NCIT: C171398 (tarlatamab).

Surgery. Central to localized disease and independently protective (HR 0.481; PMID: 39268117). Anatomic resection is performed in ~97% of operable cases (90-day mortality ~8.3%; PMID: 42341696). In stage I, sublobectomy was an effective option in one SEER analysis (PMID: 40950692).

Radiotherapy. Chemoradiotherapy improves OS/CSS in stage III; its role in stage IV is context-dependent (PMID: 42231825).

Adjuvant therapy. SCLC-type adjuvant regimens are associated with better outcomes in resected disease, though in T1-2N0M0 SEER analyses adjuvant chemotherapy did not show a significant OS/CSS benefit over surgery alone in the overall cohort (PMID: 41510101; PMID: 41153253).

Neuroendocrine-transformed disease. In EGFR-mutant NSCLC with NE transformation, durvalumab + etoposide-platinum gave ORR 43%, median OS 10.2 months (ORCHARD; PMID: 42361644).

Personalized medicine. Genomic subtyping guides therapy: YAP1-high → MEK/AXL strategies; YAP1-low/DLL3-high → DLL3/CD56 targeting (PMID: 39150543); actionable NSCLC drivers → targeted agents (PMID: 41653583).

13. Prevention

  • Primary prevention: Tobacco control and smoking cessation are the principal strategies, given the dominant smoking etiology (PMID: 36304941).
  • Secondary prevention: Low-dose CT lung cancer screening in high-risk (heavy-smoking, elderly) populations may detect early-stage disease, where surgery is most effective — though LCNEC-specific screening data are lacking.
  • Tertiary prevention: Surveillance for and management of bone/brain/liver metastases; multimodal therapy to prevent complications.
  • Immunization: For cervical LCNEC, HPV vaccination is a plausible primary preventive measure given HPV18 causation (PMID: 42521492); not applicable to pulmonary LCNEC.
  • Genetic counseling / carrier screening: Not applicable (somatic disease).

14. Other Species / Natural Disease

Species-specific data for LCNEC are limited. NCBI Taxonomy: Homo sapiens (9606). Orthologous driver genes are highly conserved across mammals (Tp53, Rb1, Kras, Stk11, Ascl1, Dll3), supporting cross-species relevance of the pathways involved. Naturally occurring high-grade neuroendocrine carcinomas are reported in companion animals (e.g., pulmonary and gastrointestinal NECs in dogs and cats via OMIA/veterinary literature), but LCNEC-specific comparative pathology was not systematically retrieved in this investigation and remains a knowledge gap. There is no zoonotic transmission (non-communicable neoplasm).

15. Model Organisms

Direct LCNEC-specific models were not the focus of the retrieved literature, but the field draws heavily on SCLC genetically engineered mouse models (GEMMs), given the SCLC-like biology of most LCNEC. GEMMs based on conditional Tp53/Rb1 inactivation (and Trp53/Rb1/Myc combinations) recapitulate high-grade neuroendocrine lung carcinoma and are used to validate driver mutations and targeted therapies (PMID: 31134494). Patient-derived xenografts (including circulating-tumor-cell–derived xenografts, CDX) and patient-derived organoids are used for high-grade NE tumors and for mixed carcinomas (e.g., an endometrial mixed LCNEC organoid/xenograft revealing PI3K/VEGF vulnerabilities; PMID: 41886729). Cell lines expressing ASCL1 and NE markers model the ASCL1 super-enhancer program (PMID: 30121393).

Model resources: MGI (mouse), Cellosaurus/ATCC (cell lines), and PDX/organoid biobanks. Limitations: Few models are LCNEC-specific (as opposed to SCLC); the NSCLC-like and YAP1-high subtypes are underrepresented; models incompletely capture the human tumor immune microenvironment and the interobserver diagnostic ambiguity.

Mechanistic Model / Interpretation

LCNEC is best understood as a lineage-plastic, tobacco-driven high-grade neuroendocrine carcinoma that molecularly bridges SCLC and NSCLC. A unifying model:

Axis SCLC-like pole NSCLC-like pole
Drivers RB1 + TP53 KEAP1/KRAS/STK11/SMARCA4/CDKN2A
Transcription factors ASCL1, NEUROD1 high —
YAP1 Low High
Surface target DLL3 high, CD56 —
Immune phenotype Immune-cold Mesenchymal, inflamed
Therapeutic vulnerability DLL3 (tarlatamab), platinum-etoposide MEK/AXL, NSCLC-driver–targeted agents

Upstream, tobacco carcinogens generate a high mutational burden and near-universal TP53 loss. The bifurcation into SCLC-like vs NSCLC-like programs — reinforced by epigenetic machinery (DNMT1/DNMT3A, ASCL1 super-enhancers, promoter hypermethylation) — determines transcription-factor identity, surface-antigen expression (notably DLL3), immune phenotype, and druggable vulnerabilities. Downstream, high-grade proliferation, necrosis, and spread-through-air-spaces produce early metastasis and poor survival. A distinct transformation route exists whereby EGFR-mutant adenocarcinoma converts to LCNEC under TKI pressure, acquiring MYC amplification atop shared clonal TP53/STK11. This model directly rationalizes emerging precision approaches: DLL3-directed T-cell engagers for the SCLC-like/ASCL1/DLL3-high pole and MEK/AXL or driver-targeted agents for the YAP1-high/NSCLC-like pole.

Evidence Base

PMID Contribution
40830141 Defines SCLC-like vs NSCLC-like genomic subtypes; DLL3-high in SCLC-like LCNEC
38159439 Large CGP cohort; SCLC-like (n=557), carcinoid-like (n=25) definitions
35641209 TMB (12.7/Mb); NOTCH/TP53 mutations; HR-pathway predicts PFS
39150543 YAP1-high vs YAP1-low subtypes and vulnerabilities
36304941 Incidence, demographics, IHC markers
28871510 Mandatory IHC (chromogranin A + synaptophysin); histologic features
31201506 STAS in 71–88% of high-grade NE carcinomas
42208366 Chemoimmunotherapy meta-analysis (ORR 49%, OS HR 0.72)
41653583 Platinum-etoposide first-line standard
39268117 SEER independent prognostic factors with HRs
42341696 EPITHOR resected 5-year OS 52.9%; demographics
41376913 Stage-selected resected 5-year survival ~86%
42491047 Tarlatamab clinical activity in LCNEC
42449715 Tarlatamab FDA approval status
42562260 Tarlatamab in DLL3-high pulmonary carcinoid (73% RR)
29378266 PD-L1/immune infiltration in high-grade lung NEC
41854102 DNMT1/DNMT3A upregulation in LCNEC
39832203 LCNEC as methylation bridge between NSCLC/SCLC
30121393 ASCL1 as master super-enhancer regulator
39868963 MYC-amplified NE transformation; clonal TP53/STK11
28768973 LCNEC transformation as EGFR-TKI resistance
41240593 Stage IV median OS 7.4 mo; 67% diagnostic confirmation
42556470 Central pathology review heterogeneity
18440724 LAT1 overexpression (52.4%) and poor outcome
42521492 Immune-cold HPV18+ cervical LCNEC, ICI resistance

Limitations and Knowledge Gaps

  1. Diagnostic reproducibility. LCNEC is confirmed in only ~67% of cases on central review, with substantial interobserver variability (PMID: 41240593; PMID: 42556470). This introduces classification bias into all registry-based epidemiology and outcomes data.
  2. Evidence quality. Much survival/treatment evidence derives from retrospective SEER/registry analyses and single-arm/case reports; prospective randomized data specific to LCNEC are scarce (FIRST-NEC is ongoing).
  3. Rarity and subtype under-sampling. NSCLC-like and YAP1-high subtypes, and extrapulmonary LCNEC, are underrepresented; treatment is largely extrapolated from SCLC/NSCLC.
  4. Quality-of-life data. No LCNEC-specific EQ-5D/SF-36/PROMIS data were identified.
  5. Model organisms. Few LCNEC-specific in vivo models exist; the field relies on SCLC GEMMs and PDX/organoids.
  6. Predictive biomarkers. Reliable biomarkers for ICI benefit and hyperprogression risk are not established.
  7. Comparative/veterinary biology. Naturally occurring LCNEC in other species is poorly characterized.

Proposed Follow-up Experiments / Actions

  1. Prospective subtype-stratified trials. Complete and expand trials like FIRST-NEC (NCT06393816) and add DLL3-directed arms (tarlatamab) for SCLC-like/DLL3-high LCNEC, and MEK/AXL inhibitor arms for YAP1-high tumors.
  2. Standardize diagnosis. Adopt the structured central-pathology-review reporting form and combine IHC + molecular subtyping (RB1 IHC, targeted NGS) to reduce misclassification (PMID: 42556470).
  3. Biomarker development. Validate DLL3, ASCL1/NEUROD1/YAP1, TMB, PD-L1, and HR-deficiency as predictive biomarkers; develop cfDNA/epigenomic liquid biopsies for transformation detection and monitoring (PMID: 38912901).
  4. Model building. Generate LCNEC-specific GEMMs and organoids representing NSCLC-like and YAP1-high subtypes for preclinical drug testing.
  5. Epigenetic therapy. Test DNMT inhibitors (given DNMT1/DNMT3A upregulation) and ASCL1/super-enhancer-directed strategies (PMID: 41854102; PMID: 30121393).
  6. Extrapulmonary registries. Establish site-specific registries (thymic, GI, gynecologic) to define subtype-specific biology and optimal therapy.
  7. Patient-reported outcomes. Collect LCNEC-specific QoL data prospectively.

Report compiled from 15 confirmed findings across 67 reviewed papers. Evidence sources span human clinical (registries, cohorts, case reports), in vitro/genomic profiling, and computational/ontology lookups.

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