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)

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

Sources

• Integrative genomic profiling of large-cell neuroendocrine carcinomas reveals distinct subtypes of high-grade neuroendocrine lung tumors (George et al., Nat Commun 2018, PMID:29535388)
• Genomic Profiling of Large-Cell Neuroendocrine Carcinoma of the Lung, Clin Cancer Res
• Molecular Pathology of Pulmonary Large Cell Neuroendocrine Carcinoma: Novel Concepts and Treatments, PMC8100606
• Genomic Profiling and Clinicopathological Characteristics of Neuroendocrine Tumors of the Lung in East Asian Patients, PMID:33144445
• Real-World comprehensive genomic profiling data for diagnostic clarity in pulmonary Large-Cell neuroendocrine carcinoma, Lung Cancer
• Integrated molecular and clinical characterization of pulmonary large cell neuroendocrine carcinoma, Nature Communications 2025
• Molecular Subtypes of Neuroendocrine Carcinoma, Annual Reviews
• New molecular classification of large cell neuroendocrine carcinoma and small cell lung carcinoma with potential therapeutic impacts, Transl Lung Cancer Res
• Molecular subtypes of neuroendocrine carcinomas: A cross-tissue classification framework based on five transcriptional regulators, Cancer Cell
• Comprehensive Analysis of NEUROD1, ASCL1, POU2F3, and YAP1 Expression Signatures Reveals Unique LCNEC Subgroups
• Prototypical oncogene family Myc defines unappreciated distinct lineage states of small cell lung cancer, Science Advances
• Differential development of large-cell neuroendocrine or small-cell lung carcinoma upon inactivation of 4 tumor suppressor genes, PNAS 2020
• TRP53 Mutants Drive Neuroendocrine Lung Cancer Through Loss-of-Function Mechanisms with Gain-of-Function Effects on Chemotherapy Response, Mol Cancer Ther
• Clinical and morphological features of large-cell neuroendocrine carcinomas and small-cell lung carcinomas expressing DLL3 and ASCL1 oncoproteins, PMC10739177
• TTF-1 and c-MYC-defined Phenotypes of Large Cell Neuroendocrine Carcinoma and DLL3 Expression for Treatment Selection, PMC8132912
• Targeting DLL3: A New Weapon in Lung Neuroendocrine Tumors?, PMC11986208
• Tarlatamab for Large Cell Neuroendocrine Carcinoma in a Young Adult: A Case Report, JTO Clin Res Rep
• Large Cell Neuroendocrine Carcinoma of the Lung: Clinico-Pathologic Features, Treatment, and Outcomes, PMC5474315
• Outcomes of Patients with Pulmonary Large Cell Neuroendocrine Carcinoma in I–IV Stage, PMC7911070
• Comprehensive Dissection of Treatment Patterns and Outcome for Patients With Metastatic LCNEC, PMC8295750
• The Effectiveness of Atezolizumab in Metastatic LCNEC: LANCE Pilot Study, PMC11200835
• Based on SEER Database: Population Distribution, Survival Analysis, and Prognostic Factors of Organ Metastasis of Lung LCNEC, PMC8971719
• The prognosis analysis of organ metastatic patterns in lung LCNEC: A population-based study, PMC9773085
• Clinicopathological characteristics, treatment and survival of pulmonary LCNEC: a SEER population-based study, PMC6441320
• Large-Cell Neuroendocrine Carcinoma of the Lung: A Population-Based Study, ScienceDirect
• Pulmonary Large Cell Neuroendocrine Carcinoma: A Rare Type of Non-Small Cell Lung Cancer, PMC8162139
• Clinicopathological characteristics and prognosis of pulmonary LCNEC aged ≥65 years, PMC6532618
• Large Cell Neuroendocrine Carcinoma of the Lung: A Case Series of 14 Cases, PMC9428409
• Survival outcomes of surgery in patients with pulmonary LCNEC, PMC7881654
• Management of Large Cell Neuroendocrine Carcinoma, Frontiers in Oncology, PMID:34513663
• Genomic profiling of high-grade large-cell neuroendocrine carcinoma of the colon, J Gastrointest Oncol
• Extrapulmonary Neuroendocrine Carcinomas: Current Management and Future Perspectives, PMC10743506
• Managing Metastatic Extrapulmonary Neuroendocrine Carcinoma After First-Line Treatment, Curr Oncol Rep
• Clinical Features and Outcomes Analysis of Surgical Resected Pulmonary LCNEC With Adjuvant Chemotherapy, PMC7736707
• Outcomes of patients with LCNEC of the lung after complete resection, Transl Cancer Res
• Outcomes for Surgery in Large Cell Lung Neuroendocrine Cancer, J Thorac Oncol
• A Phase II Basket Trial of Dual Anti-CTLA-4 and Anti-PD-1 Blockade in Rare Tumors (DART SWOG 1609) in Patients with Nonpancreatic Neuroendocrine Tumors, PMID:31969335
• Phase II basket trial DART SWOG S1609: High-grade neuroendocrine neoplasm cohort, PMID:33882143
• A Case of Paraneoplastic Neurological Syndrome Leading to the Diagnosis of LCNEC From Opsoclonus-Myoclonus Syndrome, PMC10725307
• N-staging in large cell neuroendocrine carcinoma of the lung: diagnostic value of [18F]FDG PET/CT, EJNMMI Research, PMC8298649
• Effect of Ki-67 proliferation index on survival in large cell neuroendocrine carcinoma of the lung, PMC11404992
• Pathology Outlines - Large cell neuroendocrine carcinoma
• Large cell neuroendocrine carcinoma of the lung, Wikipedia
• large cell neuroendocrine carcinoma, National Organization for Rare Disorders / MONDO
• Large Cell Neuroendocrine Carcinoma of the Lung: Current Understanding and Challenges, PMC8911276
• Large Cell Neuro-Endocrine Carcinoma of the Lung: Current Treatment Options and Potential Future Opportunities, PMC8081906
• Large cell neuroendocrine lung carcinoma: consensus statement from The British Thoracic Oncology Group and the Association of Pulmonary Pathologists, Br J Cancer

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Large Cell Neuroendocrine Carcinoma: Disease-Characteristics Report

Scope and evidence note

Large cell neuroendocrine carcinoma (LCNEC) is a morphologic category of poorly differentiated, high-grade epithelial neuroendocrine carcinoma, not a single inherited syndrome. It most often refers to pulmonary LCNEC; morphologically similar carcinomas occur in the gastrointestinal, pancreatic, genitourinary, gynecologic, head-and-neck, and other organs. Because pulmonary disease dominates the evidence base, findings should not automatically be transferred to extrapulmonary LCNEC. Most evidence is aggregated disease-level evidence from pathology cohorts, registries, retrospective clinical series, and reviews—not individual-patient EHR evidence.

The following table provides a compact knowledge-base summary; the narrative afterward expands the requested domains.

Table: Compact comparison of pulmonary LCNEC and extrapulmonary large-cell or poorly differentiated neuroendocrine carcinoma, covering classification, molecular biology, clinical features, management, prognosis, prevention, and models.

1. Disease information

Definition and classification

LCNEC is defined by: (1) neuroendocrine architecture, such as organoid nests, trabeculae, peripheral palisading, or rosettes; (2) large-cell/non-small-cell cytology with abundant cytoplasm, vesicular or coarse chromatin, and often prominent nucleoli; (3) extensive proliferation and usually necrosis; and (4) neuroendocrine differentiation demonstrated by morphology and immunohistochemistry. Pulmonary LCNEC was described as a distinct entity in 1991, categorized as a large-cell/NSCLC variant in the 1999–2004 WHO schemes, and moved into the pulmonary neuroendocrine-carcinoma family in 2015, a concept retained in WHO 2021. Biologically it often resembles SCLC more than conventional NSCLC. (yang2022pulmonarylargecell pages 1-2, yang2022pulmonarylargecell pages 3-4)

A useful exact abstract statement from Yang et al. (published 11 October 2022) is: “Pulmonary large cell neuroendocrine carcinoma (LCNEC) is a rare subtype of malignant pulmonary tumor.” The review further reports that LCNEC is more aggressive than other NSCLC and has behavior similar to SCLC. DOI/URL. (yang2022pulmonarylargecell pages 2-3, yang2022pulmonarylargecell pages 1-2)

Identifiers and synonyms

• MONDO: MONDO:0005057, large cell neuroendocrine carcinoma; MONDO:0003960, pulmonary large cell neuroendocrine carcinoma. Site-specific MONDO entries include pancreatic LCNEC (MONDO:0006347) and ovarian large-cell neuroendocrine carcinoma (MONDO:0003049). (OpenTargets Search: large cell neuroendocrine carcinoma)
• Synonyms: LCNEC; large-cell neuroendocrine carcinoma; large-cell neuroendocrine cancer; pulmonary LCNEC; lung LCNEC; large-cell poorly differentiated neuroendocrine carcinoma. “High-grade neuroendocrine carcinoma” is broader and also includes small-cell NEC.
• MeSH: no uniquely specific LCNEC descriptor was established in the retrieved evidence; indexing commonly uses Carcinoma, Neuroendocrine plus the anatomic-site neoplasm.
• ICD: ICD-O morphology coding is more appropriate than a single ICD-10 diagnosis code. ICD-10-CM and ICD-11 generally combine anatomic-site malignancy coding with neuroendocrine histology; a universally specific cross-organ LCNEC code was not established in the retrieved sources.
• OMIM/Orphanet: no Mendelian OMIM disease entry or established inherited LCNEC syndrome was identified. LCNEC is principally a sporadic somatic neoplasm.

2. Etiology, risk, and protective factors

Causal and risk factors

Pulmonary LCNEC has a strong tobacco association: patients are usually older, male, heavy smokers, and one synthesis found a smoking history in 92.8%. Mean diagnostic age is approximately 60–70 years. The defensible causal chain is chronic tobacco-carcinogen exposure → accumulated somatic DNA damage and clonal selection → loss of cell-cycle/genome-surveillance pathways, often TP53 and RB1 or STK11/KEAP1-associated pathways → high-grade neuroendocrine lineage programs → invasive and metastatic carcinoma. Smoking is therefore the principal established environmental risk factor, although LCNEC-specific dose-response and attributable-risk estimates remain limited. (yang2022pulmonarylargecell pages 2-3, yang2022pulmonarylargecell pages 1-2)

For extrapulmonary LCNEC, risks are organ dependent. Some cervical cases can be HPV-associated, whereas prostate neuroendocrine carcinoma may emerge under androgen-receptor pathway treatment pressure; neither mechanism should be generalized to pulmonary LCNEC. No infectious agent is established as a universal LCNEC cause.

Genetic susceptibility, protective factors, and gene–environment interaction

The recurrent alterations described below are overwhelmingly somatic tumor alterations, not inherited causal variants. No reproducible LCNEC-specific germline susceptibility locus, protective allele, founder mutation, carrier frequency, Mendelian inheritance pattern, anticipation, or consanguinity effect is established. Consequently, population allele frequencies and ACMG germline pathogenicity classifications are generally not applicable to the common tumor-driver profile.

No LCNEC-specific protective drug, diet, supplement, or exercise intervention has demonstrated risk reduction. Tobacco avoidance and cessation are the best-supported environmental protective measures by inference from the strong smoking association. Formal LCNEC-specific gene–environment interaction studies are lacking; tobacco exposure plausibly interacts with deficient TP53/RB1-mediated checkpoint control, but quantitative G×E estimates are unavailable.

3. Phenotypes

Pulmonary LCNEC is typically adult/late-onset, insidious, severe, and progressive. It may be detected incidentally. Presenting symptoms are nonspecific and include cough, chest pain, hemoptysis, dyspnea, constitutional decline, and manifestations of local compression. Suggested HPO mappings include Cough (HP:0012735), Hemoptysis (HP:0002105), Dyspnea (HP:0002094), Chest pain (HP:0100749), Fatigue (HP:0012378), and Weight loss (HP:0001824). Exact frequency estimates for individual presenting symptoms are not robustly established. (yang2022pulmonarylargecell pages 2-3, yang2022pulmonarylargecell pages 1-2)

Disease commonly spreads to liver, bone, brain, adrenal glands, and lymph nodes. Suggested terms include Neoplasm metastatic to liver (HP:0002896), Neoplasm metastatic to bone (HP:0002797), and brain metastasis as a clinical-neoplasm annotation. In a 52-patient Vienna brain-metastasis cohort, 76.9% were neurologically symptomatic: 24 had neurologic deficits, 18 increased intracranial pressure, and 6 seizures; 51.9% had one brain metastasis and 23% had more than three. Suggested HPO terms include Seizure (HP:0001250), Increased intracranial pressure (HP:0002516), Headache (HP:0002315), and focal neurologic deficit terms selected per manifestation. (popov2024clinicalcharacteristicstreatment pages 1-2)

Classic functioning-neuroendocrine syndromes are uncommon in pulmonary LCNEC. Hormonal laboratory abnormalities or paraneoplastic syndromes can occur in high-grade NEC generally, but LCNEC-specific frequencies are not established. Quality-of-life studies using EQ-5D, SF-36, or LCNEC-specific instruments are scarce; the principal impacts are respiratory limitation, neurologic disability from brain metastases, treatment toxicity, pain, impaired work/daily activity, and psychological burden.

4. Genetic and molecular information

Somatic drivers and molecular classes

Reported pulmonary LCNEC mutation frequencies include TP53 82.3%, RB1 39.1%, KEAP1 20.9%, STK11 18.2%, KRAS 12.7%, and EGFR 11.9%. Open Targets additionally associates LCNEC with SMARCA4, CDKN2A, BRAF, and IDH2. These are tumor-level associations and do not prove germline causation. (OpenTargets Search: large cell neuroendocrine carcinoma, yang2022pulmonarylargecell pages 3-4)

Three practical genomic patterns are recognized:

1. SCLC-like: TP53/RB1 co-mutation, deletion, or protein loss; converges on defective p53-mediated DNA-damage responses and RB/E2F cell-cycle restriction.
2. NSCLC-like: often RB1-intact, with STK11, KEAP1, and/or KRAS alterations; these affect AMPK–mTOR metabolic sensing, NRF2 oxidative-stress regulation, and RAS–MAPK signaling.
3. Carcinoid-like/rare: MEN1-associated patterns, likely representing a biologically distinct minority or diagnostic boundary group. (popov2024clinicalcharacteristicstreatment pages 1-2, yang2022pulmonarylargecell pages 3-4, corti2024emergingtreatmentoptions pages 14-16)

Variants include missense and truncating mutations, deletions/copy-number loss, amplifications, and occasional rearrangements. Their exact HGVS distribution and gnomAD frequency are not meaningful without a specified case because they are heterogeneous somatic events. For clinical annotation, variants should be recorded using AMP/ASCO/CAP somatic tiers rather than automatically labeled germline “pathogenic” under ACMG criteria.

2024 lineage and target findings

A 2024 resection study of 146 pulmonary NECs identified a POU2F3-dominant tuft-cell-like phenotype. It included 14 POU2F3-dominant LCNECs, 27 ASCL1-dominant LCNECs, and 10 triple-negative LCNECs; no NEUROD1-dominant LCNEC was found. POU2F3-dominant SCLC and LCNEC overlapped morphologically and showed lower TTF-1, CEA, and conventional neuroendocrine-marker expression but higher BCL2, MYC, and KIT. POU2F3 correlated inversely with synaptophysin (ρ=−0.67) and positively with KIT (ρ=0.60). LCNEC-P showed RB1 loss in 64% versus 35% of LCNEC-non-P, although the difference was not significant. POU2F3-dominant NEC had better recurrence-free survival but all patients were smokers, underscoring a lineage–exposure relationship requiring validation. Published October 2024; DOI/URL. (jimbo2024pou2f3expressingsmallcell pages 1-9, jimbo2024pou2f3expressingsmallcell pages 21-27, jimbo2024pou2f3expressingsmallcell pages 27-32, jimbo2024pou2f3expressingsmallcell pages 9-15)

DLL3, an inhibitory Notch ligand downstream of ASCL1, is minimally expressed in most normal tissues but enriched in SCLC, LCNEC, and combined pulmonary NEC. A 2024 standardized-IHC study evaluated 548 suitable specimens and found heterogeneous expression across pulmonary and extrapulmonary high-grade NENs. Another stage-IV LCNEC cohort reported DLL3-high expression in 74%, including 6/6 STK11-mutant and 10/11 KEAP1-mutant tumors. Published November 2024; DOI/URL. (serrano2024deltalikeligand3 pages 1-2, serrano2024deltalikeligand3 pages 10-11, peddio2024dll3asa pages 1-3)

A February 2024 targeted-sequencing study of 257 patients—99 GEP-NECs, 57 lung NECs, and 101 digestive adenocarcinomas—showed organ-specific biology: TERT amplification in gastric NEC, KRAS mutation in colorectal NEC, and ARID1A mutation in biliary NEC; small- versus large-cell NEC differed in KEAP1 and CDH1. Potentially targetable alterations/biomarkers occurred in 22.2% of GEP-NECs. Genotype-matched treatment was associated with PFS of 12.5 versus 3.0 months (HR 0.40; p=0.006), though this nonrandomized result is vulnerable to selection bias. DOI/URL. (zhang2024molecularfeaturesof pages 1-2)

Epigenetic and structural information

SMARCA4 loss implicates SWI/SNF chromatin-remodeling dysfunction; POU2F3, ASCL1, and NEUROD1 identify lineage-regulatory states rather than single causal lesions. However, LCNEC-specific methylome, histone-mark, chromatin-accessibility, single-cell, spatial-transcriptomic, proteomic, metabolomic, and lipidomic datasets remain limited. No recurrent pathognomonic translocation or aneuploidy defines LCNEC. Copy-number losses of RB1/CDKN2A and amplifications such as TERT or MYC-family changes may occur, depending on site and subtype.

5. Environmental and lifestyle information

Tobacco smoke is the principal established exposure for pulmonary LCNEC. No LCNEC-specific evidence establishes alcohol, diet, exercise, ambient pollution, radiation, occupational toxins, or infection as independent causal factors, although standard lung-cancer risks remain biologically plausible. For cervical LCNEC, HPV testing is relevant; for pulmonary LCNEC, HPV is not an established cause. There is no zoonotic or transmissible component.

6. Mechanism and pathophysiology

Causal chain

Upstream: carcinogenic exposure or site-specific oncogenic pressure produces somatic mutations and copy-number changes. Core transformation: loss of TP53 disables DNA-damage checkpoints and apoptosis; RB1 loss releases E2F-driven S-phase entry. In NSCLC-like disease, STK11 loss alters AMPK/mTOR control, KEAP1 loss activates NRF2-dependent antioxidant programs, and KRAS activates MAPK signaling. Lineage specification: ASCL1/NEUROD1 or POU2F3 programs establish neuroendocrine or tuft-cell-like states; ASCL1 can induce DLL3, which suppresses Notch signaling. Downstream: unchecked cell cycling, genomic instability, resistance to apoptosis, metabolic adaptation, extensive necrosis, stromal remodeling, invasion, hematogenous dissemination, and treatment resistance produce the observed aggressive phenotype. (yang2022pulmonarylargecell pages 3-4, serrano2024deltalikeligand3 pages 1-2, jimbo2024pou2f3expressingsmallcell pages 1-9)

Relevant GO suggestions include regulation of cell cycle (GO:0051726), DNA damage response (GO:0006974), apoptotic process (GO:0006915), MAPK cascade (GO:0000165), response to oxidative stress (GO:0006979), Notch signaling pathway (GO:0007219), neuroendocrine cell differentiation, angiogenesis (GO:0001525), and cell migration (GO:0016477). Cell Ontology suggestions include pulmonary neuroendocrine cell (CL:0000450), epithelial cell, tuft cell, T lymphocyte, macrophage, endothelial cell, and fibroblast; the exact cell of origin is not conclusively established.

Immune involvement is heterogeneous. CD8-positive T-cell infiltration has been associated with prognosis, but STK11/KEAP1-altered tumors may exhibit relatively immune-cold biology. PD-L1 and tumor-mutational burden are imperfect predictive biomarkers. DLL3’s restricted surface expression provides a route for bispecific T-cell engagers, CAR-T cells, antibody–drug conjugates, or radioligands. (yang2022pulmonarylargecell pages 7-8, serrano2024deltalikeligand3 pages 1-2, serrano2024deltalikeligand3 pages 10-11)

Subcellular ontology suggestions include nucleus (GO:0005634) for TP53/RB1/transcriptional programs, chromatin (GO:0000785) for SMARCA4 dysfunction, plasma membrane (GO:0005886) for DLL3/KIT/receptor targets, and mitochondrion (GO:0005739) for oxidative/metabolic adaptation.

7. Anatomical structures affected

Pulmonary LCNEC usually arises as a peripheral lung mass, often in an upper lobe and frequently the right upper lobe. Mediastinal and hilar lymph-node involvement is common. Suggested UBERON annotations are lung (UBERON:0002048), lung lobe, bronchus (UBERON:0002185), pulmonary epithelium, hilar lymph node, and mediastinal lymph node. Imaging may show lobulation, irregular or spiculated margins, emphysema, notching, pleural indentation, cavitation, and nodal enlargement. No consistent lateralization exists. (yang2022pulmonarylargecell pages 2-3, yang2022pulmonarylargecell pages 7-8)

Secondary organs include brain, liver, skeleton, adrenal gland, and lymphatic sites. Extrapulmonary LCNEC can arise in essentially any epithelial organ; approximately 37% of extrapulmonary NECs occur in the gastroenteropancreatic tract, followed by genitourinary and gynecologic systems. This 37% statistic concerns EP-NEC overall, not LCNEC alone. (stumpo2023extrapulmonaryneuroendocrinecarcinomas pages 15-17)

8. Temporal development

Onset is usually insidious in older adults rather than congenital or pediatric. LCNEC progresses rapidly and is often regionally advanced or metastatic at recognition. Pulmonary disease is staged with the lung-cancer TNM system; extrapulmonary disease uses the relevant organ-specific TNM framework.

Postoperative recurrence is frequent: 63.9%–82% within one year and 91% within two years in reported series, commonly involving mediastinal or supraclavicular nodes. Remission is generally treatment-induced, not spontaneous, and relapse after platinum sensitivity is common. The principal intervention window is complete resection of localized disease followed by consideration of adjuvant systemic treatment; in advanced disease, early molecular profiling and clinical-trial referral are important because durable standard options are limited. (yang2022pulmonarylargecell pages 7-8)

9. Inheritance and population epidemiology

Pulmonary LCNEC represents approximately 0.3%–3% of lung cancers and 2.1%–3.5% of surgically resected lung cancers. Incidence may be underestimated because cytology and small biopsies commonly misclassify it. Patients are predominantly men, heavy smokers, and age 60–70 years. Robust population incidence per 100,000 person-years, prevalence, ethnicity-specific rates, and geographic variation are not consistently established. (yang2022pulmonarylargecell pages 2-3)

LCNEC is sporadic and somatically driven; inheritance, penetrance, expressivity, anticipation, germline mosaicism, founder effects, carrier frequency, and consanguinity are not applicable to typical cases. Genetic counseling is indicated only when personal/family history or tumor findings suggest an independent hereditary cancer syndrome.

10. Diagnostics

Pathology and immunohistochemistry

WHO 2021 pulmonary criteria require neuroendocrine architecture, large-cell cytology, and >10 mitoses/2 mm², typically 60–80/2 mm²; necrosis is often extensive. At least one neuroendocrine marker—synaptophysin, chromogranin A, or CD56/NCAM1—should support differentiation. INSM1 is positive in approximately 68%–91.3% and is a useful nuclear adjunct; TTF-1 is positive in approximately 54.8%. Ki-67 is usually high and useful in crushed biopsies but does not independently establish LCNEC. (yang2022pulmonarylargecell pages 2-3, yang2022pulmonarylargecell pages 3-4)

Small biopsies are problematic because architecture, mitotic rate, necrosis, and cytologic size may be undersampled. Expert thoracic-pathology review and sufficient tissue are therefore valuable. POU2F3 IHC can identify a neuroendocrine-marker-low tuft-cell-like group and explain SCLC/LCNEC overlap. (jimbo2024pou2f3expressingsmallcell pages 1-9, jimbo2024pou2f3expressingsmallcell pages 27-32)

Imaging, laboratory tests, and biomarkers

Contrast-enhanced chest CT defines the primary tumor and nodes; FDG-PET/CT supports systemic staging. Brain MRI is appropriate for neurologic symptoms and generally for advanced disease because brain metastases occur in approximately 19.2%–20% overall and up to 35% of stage-IV cases. CT/MRI of abdomen and pelvis evaluates liver and adrenal spread. Somatostatin-receptor imaging is less consistently informative than in well-differentiated NET and should be individualized. (popov2024clinicalcharacteristicstreatment pages 1-2)

Routine blood counts, renal/hepatic function, electrolytes, and treatment-baseline tests are necessary but nonspecific. CEA, NSE, proGRP, chromogranin A, and circulating tumor DNA can be investigated, but no serum biomarker is sufficiently sensitive and specific for diagnosis or screening. Liquid biopsy is promising for tumor genotyping and monitoring but is not a histologic substitute.

Molecular testing

For advanced disease, a broad somatic NGS panel is reasonable, including TP53, RB1, STK11, KEAP1, KRAS, BRAF, EGFR, ALK, RET, NTRK1/2/3, ERBB2, MET, IDH2, SMARCA4, CDKN2A, APC, ARID1A, and MSI/TMB assessment. RB1 status may help choose an SCLC-like versus NSCLC-like chemotherapy strategy, although this remains incompletely validated. WES/WGS and RNA-seq can detect uncommon fusions or clarify lineage but are not routine diagnostic necessities; CMA, karyotyping, mitochondrial testing, and repeat-expansion testing have no standard role. (OpenTargets Search: large cell neuroendocrine carcinoma, corti2024emergingtreatmentoptions pages 14-16, zhang2024molecularfeaturesof pages 1-2)

Differential diagnosis and screening

The differential includes SCLC, basaloid or poorly differentiated squamous carcinoma, adenocarcinoma with focal neuroendocrine-marker expression, carcinoid/NET G3, SMARCA4-deficient thoracic tumor, lymphoma, melanoma, and metastatic NEC. A non-neuroendocrine NSCLC component supports combined LCNEC; an SCLC component is classified as combined SCLC. (yang2022pulmonarylargecell pages 3-4)

There is no LCNEC-specific population screening test. Eligible smokers should receive standard low-dose CT lung-cancer screening according to national criteria; suspicious lesions still require tissue diagnosis.

11. Outcome and prognosis

Pulmonary LCNEC has survival comparable to SCLC and poorer than most conventional NSCLCs. Reported stage-I five-year survival ranges widely from 27% to 67%, reflecting cohort selection and treatment differences. Adverse factors include advanced TNM stage, larger tumor, older age, high neutrophil-to-lymphocyte ratio, prior malignancy, distant metastasis, and synchronous brain metastasis; immune infiltration, KEAP1 status, POU2F3 phenotype, and RB1 status are investigational modifiers. (yang2022pulmonarylargecell pages 7-8, jimbo2024pou2f3expressingsmallcell pages 1-9)

In the 2024 Vienna cohort, median OS was 16 months from LCNEC diagnosis and 7 months after brain-metastasis diagnosis. Synchronous brain metastasis conferred median OS of 11 versus 27 months for metachronous disease (p=0.003). The paper’s abstract states: “Patients with LCNEC and BM have a poor prognosis, particularly when synchronous BM are present.” Published online 8 December 2023; journal issue 2024; DOI/URL. (popov2024clinicalcharacteristicstreatment pages 1-2)

Long-term morbidity includes recurrent thoracic disease, respiratory compromise, pain, neurologic disability, treatment-related cytopenias/neuropathy/renal injury, and reduced independence. LCNEC-specific validated quality-of-life statistics and disability weights are not available.

12. Treatment

Localized pulmonary LCNEC

Complete anatomic resection—typically lobectomy with systematic nodal evaluation—is favored when operable. Surgery alone is often inadequate because of early recurrence, so platinum-based adjuvant chemotherapy is commonly considered, especially for stage II–III and high-risk stage I disease. Evidence remains mostly retrospective. A 2024 real-world resection study of pulmonary high-grade NEC found early stage, younger age, minimally invasive surgery, and normal preoperative CEA favorable; within LCNEC, VATS was associated with improved OS and DFS, but causal interpretation is limited by selection bias. DOI/URL. (yang2022pulmonarylargecell pages 7-8)

Suggested NCIt intervention mappings: Lobectomy; Pneumonectomy; Lymph Node Dissection; Cisplatin; Carboplatin; Etoposide; Adjuvant Chemotherapy.

Advanced pulmonary LCNEC

Platinum–etoposide remains the most commonly used first-line regimen. Small retrospective series report ORRs of 50%–73% and median OS of 9.2–44 months, with substantial heterogeneity. Platinum–irinotecan is an alternative. Molecularly, TP53/RB1-altered tumors may behave more SCLC-like, whereas RB1-wild-type/STK11–KEAP1–KRAS tumors may benefit more from an NSCLC-type platinum–gemcitabine or platinum–taxane regimen; this is an expert precision-oncology strategy, not a universally proven standard. Second-line amrubicin produced ORR 27.7% and median OS 5.1 months in one report. (yang2022pulmonarylargecell pages 5-7, corti2024emergingtreatmentoptions pages 14-16)

Thoracic radiotherapy was not associated with an OS benefit in stage I–II retrospective analyses but was beneficial in stage III (p<0.001). In stage III–IV cohorts, chest radiotherapy plus prophylactic cranial irradiation was associated with median PFS of 20.5 versus 6.4 months and OS of 33.4 versus 8.6 months, although PCI comparisons were not unequivocally significant. Brain metastases are treated with resection, stereotactic radiosurgery, whole-brain radiotherapy, and systemic therapy according to number, size, symptoms, and extracranial control. Routine prophylactic cranial irradiation is not established for LCNEC. (popov2024clinicalcharacteristicstreatment pages 1-2, yang2022pulmonarylargecell pages 5-7)

Immunotherapy and targeted therapy

Retrospective pulmonary data suggest activity of PD-1/PD-L1 blockade: one series reported partial remission in 60% of PD-L1-positive patients; another found median OS of 12.4 versus 6.0 months with versus without checkpoint inhibition. These observations are nonrandomized and cannot establish efficacy. (yang2022pulmonarylargecell pages 5-7)

Actionable alterations should be treated according to tumor-agnostic or organ-specific evidence where appropriate: BRAF V600E, KRAS G12C, NTRK/ALK/RET fusions, MSI-high/dMMR, TMB-high, and selected EGFR or ERBB2 alterations. In small NEN subsets, NTRK inhibitors achieved ORR 40% among five patients; pralsetinib produced responses in two of three RET-fusion NENs. Such tiny basket subsets support testing, not LCNEC-wide efficacy. (corti2024emergingtreatmentoptions pages 14-16)

DLL3 is a leading emerging target. Its high prevalence and minimal normal-tissue expression support bispecific antibodies, CAR-T cells, antibody–drug conjugates, and alpha-radioligands. However, expression is heterogeneous and LCNEC-specific response data remain immature. In platinum-treated LCNEC, DLL3 positivity did not significantly alter five-year OS (58.3% versus 35.7%; p=0.36) or recurrence-free survival (41.7% versus 35.7%; p=0.74). (serrano2024deltalikeligand3 pages 1-2, serrano2024deltalikeligand3 pages 10-11, peddio2024dll3asa pages 1-3)

Extrapulmonary LCNEC

Localized disease may receive surgery or chemoradiation. Advanced extrapulmonary poorly differentiated NEC is generally treated with platinum–etoposide, mirroring SCLC; no consensus second-line standard exists. Site, morphology, Ki-67, molecular profile, organ function, and performance status should guide subsequent FOLFIRI, FOLFOX, taxane/irinotecan, temozolomide-based, immunotherapy, or targeted approaches. A 2023 review’s abstract accurately summarizes current expert opinion: “Platinum-based chemotherapy currently represents the standard of care for EP-NECs of any site.” Published December 2023; DOI/URL. (stumpo2023extrapulmonaryneuroendocrinecarcinomas pages 15-17)

Current trials and advanced therapeutics

• NCT05470595: phase II, single-arm atezolizumab plus platinum/etoposide for advanced pulmonary LCNEC; 67 participants; active, not recruiting. Exact registry title: “A Single-arm Trial of Atezolizumab/Platinum/Etoposide for the Treatment of Advanced Large-cell Neuroendocrine Cancer of the Lung.” ClinicalTrials.gov. (NCT05470595 chunk 2)
• NCT06418087: phase II durvalumab with carboplatin/etoposide in pulmonary LCNEC; recruiting; planned n=49. ClinicalTrials.gov.
• NCT06393816 (FIRST-NEC): phase II durvalumab plus platinum/etoposide in NEC; recruiting; planned n=80. ClinicalTrials.gov.
• NCT06049966: phase I atezolizumab in LCNEC; completed; n=22. ClinicalTrials.gov.
• NCT06736418: phase I ^225Ac-ABD147 in previously platinum-treated SCLC or pulmonary LCNEC; active, not recruiting; n=17. ClinicalTrials.gov.
• NCT04079712: phase II cabozantinib plus nivolumab/ipilimumab in poorly differentiated NEC; active, not recruiting; n=17. ClinicalTrials.gov.
• NCT05680922: phase I LB2102 DLL3-directed CAR-T therapy is principally an extensive-stage SCLC study, not an established LCNEC trial; active, not recruiting; n=41. ClinicalTrials.gov. Its exact title is “DLL3-Directed Chimeric Antigen Receptor T-cells in Subjects With Extensive Stage Small Cell Lung Cancer.” (NCT05680922 chunk 2)

No approved gene-replacement, CRISPR, antisense, siRNA, or LCNEC-specific cell therapy exists. Toxicity follows the intervention: platinum causes myelosuppression, nephrotoxicity, ototoxicity, and neuropathy; etoposide causes marrow suppression and alopecia; checkpoint blockade causes immune-related adverse events; DLL3 T-cell engagers/CAR-T approaches can cause cytokine-release and neurotoxicity syndromes.

13. Prevention

Primary prevention: avoid tobacco initiation, promote cessation, and reduce secondhand-smoke and occupational carcinogen exposure. No LCNEC-specific vaccine or chemopreventive agent exists.

Secondary prevention: no LCNEC-specific screening program exists. Standard low-dose CT screening for eligible high-risk smokers may detect pulmonary LCNEC incidentally. There is no newborn, carrier, prenatal, preimplantation, or cascade screening indication for sporadic LCNEC.

Tertiary prevention: complete staging, smoking cessation after diagnosis, vaccination and infection prevention during systemic therapy, thromboembolism assessment, surveillance imaging, early management of brain metastases, nutrition, pain/palliative care, and rehabilitation can reduce complications. Prophylactic cranial irradiation is not established routinely.

14. Other species and natural disease

Naturally occurring neuroendocrine carcinomas are reported in veterinary species, but no well-defined breed-specific, epidemiologically validated natural LCNEC counterpart was established in the retrieved evidence. Consequently, VBO breed identifiers, veterinary incidence, and conserved spontaneous causal variants cannot be assigned confidently. LCNEC is neither infectious nor zoonotic and has no cross-species transmission.

Orthologs of key drivers—including Trp53, Rb1, Stk11, Keap1, Kras, Smarca4, and Pou2f3—are conserved in Mus musculus (NCBI Taxonomy 10090), supporting mechanistic modeling, but orthology does not imply inherited natural disease.

15. Model organisms and experimental systems

Pulmonary LCNEC models

Recuero et al. developed the 46LCNEC murine line from spontaneous LCNEC arising in a CMV-QKO genetically engineered mouse model. It forms syngeneic allografts in immunocompetent and immunodeficient mice, retains the parental LCNEC transcriptomic signature, grows rapidly, and permits controlled efficacy and immunotherapy studies. The abstract states: “RNA-seq analysis demonstrated that our cell lines and syngeneic tumors maintained the transcriptome program from the original transgenic primary tumor and displayed strong similarities to human SCLC or LCNEC.” Published October 2023; DOI/URL. (recuero2023novelmousecell pages 1-2, recuero2023novelmousecell pages 7-8)

The model’s strengths are reproducibility, high penetrance, defined tumor number, low relative cost, and an intact immune system in syngeneic hosts. Limitations are murine biology, incomplete human genomic heterogeneity, and multifocal GEMM tumors at different progression stages, which can bias response assessment. (recuero2023novelmousecell pages 7-8)

Extrapulmonary models

HROC57 is a BRAF-mutant colorectal large-cell NEC cell-line/PDX pair. It was sensitive to etoposide, cisplatin, and 5-fluorouracil and resistant to rapamycin, broadly paralleling clinical NEC sensitivity. Colorectal NEC organoids formed a distinct transcriptomic group; both analyzed organoids carried TP53 mutations, while one also carried APC, BRAF, and KRAS alterations. WNT/R-spondin dependence varied with APC genotype. (detjen2021modelsofgastroenteropancreatic pages 9-10)

Patient-derived NEC PDXs NEC913 and NEC1452 had >80% Ki-67 positivity and TP53/RB1 loss; NEC913 retained SSTR2 and enabled octreotide-targeted imaging, whereas NEC1452 was SSTR2-negative. These represent high-grade GEP-NEC rather than universally validated LCNEC models.

Across the field, cell lines enable perturbation and drug screening; organoids preserve genotype–phenotype relationships; PDXs preserve tumor architecture but lack an intact human immune system; syngeneic models permit immunology; and GEMMs address initiation/evolution but may not reproduce human tobacco mutagenesis. Model scarcity and inconsistent molecular characterization remain major barriers.

Knowledge-base conclusions and evidence gaps

1. LCNEC is a pathology-defined, high-grade somatic cancer, not a Mendelian disease. Pulmonary and extrapulmonary forms should receive distinct site annotations.
2. TP53/RB1 versus STK11/KEAP1/KRAS biology is the most clinically relevant molecular division, but prospective treatment assignment remains unproven. (popov2024clinicalcharacteristicstreatment pages 1-2, yang2022pulmonarylargecell pages 3-4, corti2024emergingtreatmentoptions pages 14-16)
3. 2024 developments include POU2F3-defined tuft-cell-like LCNEC, cross-tissue genomic comparisons, broad DLL3 profiling, and dedicated pulmonary chemoimmunotherapy trials. (serrano2024deltalikeligand3 pages 1-2, zhang2024molecularfeaturesof pages 1-2, jimbo2024pou2f3expressingsmallcell pages 1-9)
4. Histology plus neuroendocrine IHC remains essential; genomics supplements but does not replace morphology.
5. Major gaps include LCNEC-specific incidence per 100,000, prospective randomized treatment data, validated predictive biomarkers, patient-reported outcomes, germline/G×E evidence, epigenomic and spatial/single-cell atlases, and representative human models.

References

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2. (yang2022pulmonarylargecell pages 1-2): Lan Yang, Ying Fan, and Hongyang Lu. Pulmonary large cell neuroendocrine carcinoma. Pathology and Oncology Research, Oct 2022. URL: https://doi.org/10.3389/pore.2022.1610730, doi:10.3389/pore.2022.1610730. This article has 54 citations.

3. (stumpo2023extrapulmonaryneuroendocrinecarcinomas pages 15-17): Sara Stumpo, Maria Giovanna Formelli, Irene Persano, Elena Parlagreco, Eleonora Lauricella, Maria Grazia Rodriquenz, Luigi Pio Guerrera, Ina Valeria Zurlo, Davide Campana, Maria Pia Brizzi, Mauro Cives, Anna La Salvia, and Giuseppe Lamberti. Extrapulmonary neuroendocrine carcinomas: current management and future perspectives. Dec 2023. URL: https://doi.org/10.3390/jcm12247715, doi:10.3390/jcm12247715. This article has 26 citations.

4. (yang2022pulmonarylargecell pages 3-4): Lan Yang, Ying Fan, and Hongyang Lu. Pulmonary large cell neuroendocrine carcinoma. Pathology and Oncology Research, Oct 2022. URL: https://doi.org/10.3389/pore.2022.1610730, doi:10.3389/pore.2022.1610730. This article has 54 citations.

5. (zhang2024molecularfeaturesof pages 1-2): Jianwei Zhang, Hanxiao Chen, Junli Zhang, Sha Wang, Yanfang Guan, Wenguang Gu, Jie Li, Xiaotian Zhang, Jian Li, Xicheng Wang, Zhihao Lu, Jun Zhou, Zhi Peng, Yu Sun, Yang Shao, Lin Shen, Minglei Zhuo, and Ming Lu. Molecular features of gastroenteropancreatic neuroendocrine carcinoma: a comparative analysis with lung neuroendocrine carcinoma and digestive adenocarcinomas. Chinese journal of cancer research = Chung-kuo yen cheng yen chiu, 36 1:90-102, Feb 2024. URL: https://doi.org/10.21147/j.issn.1000-9604.2024.01.09, doi:10.21147/j.issn.1000-9604.2024.01.09. This article has 6 citations.

6. (OpenTargets Search: large cell neuroendocrine carcinoma): Open Targets Query (large cell neuroendocrine carcinoma, 23 results). Buniello, A. et al. (2025). Open Targets Platform: facilitating therapeutic hypotheses building in drug discovery. Nucleic Acids Research.

7. (jimbo2024pou2f3expressingsmallcell pages 1-9): Naoe Jimbo, Chiho Ohbayashi, Maiko Takeda, Tomomi Fujii, Suguru Mitsui, Ryuko Tsukamoto, Yugo Tanaka, Tomoo Itoh, and Yoshimasa Maniwa. Pou2f3-expressing small cell lung carcinoma and large cell neuroendocrine carcinoma show morphologic and phenotypic overlap. The American Journal of Surgical Pathology, 48:4-15, Oct 2024. URL: https://doi.org/10.1097/pas.0000000000002145, doi:10.1097/pas.0000000000002145. This article has 29 citations.

8. (popov2024clinicalcharacteristicstreatment pages 1-2): Petar Popov, Ariane Steindl, Ladislaia Wolff, Elisabeth S. Bergen, Franziska Eckert, Josa M Frischer, Georg Widhalm, Thorsten Fuereder, Markus Raderer, Anna S. Berghoff, Matthias Preusser, and Barbara Kiesewetter. Clinical characteristics, treatment, and outcome of patients with large cell neuroendocrine carcinoma of the lung and brain metastases – data from a tertiary care center. Clinical & Experimental Metastasis, 41:25-32, Dec 2024. URL: https://doi.org/10.1007/s10585-023-10250-6, doi:10.1007/s10585-023-10250-6. This article has 13 citations and is from a peer-reviewed journal.

9. (corti2024emergingtreatmentoptions pages 14-16): Francesca Corti, Roberta Elisa Rossi, Pietro Cafaro, Gaia Passarella, Antonella Turla, Sara Pusceddu, Jorgelina Coppa, Simone Oldani, Alessandro Guidi, Raffaella Longarini, and Diego Luigi Cortinovis. Emerging treatment options for neuroendocrine neoplasms of unknown primary origin: current evidence and future perspectives. Cancers, 16:2025, May 2024. URL: https://doi.org/10.3390/cancers16112025, doi:10.3390/cancers16112025. This article has 5 citations.

10. (yang2022pulmonarylargecell pages 9-9): Lan Yang, Ying Fan, and Hongyang Lu. Pulmonary large cell neuroendocrine carcinoma. Pathology and Oncology Research, Oct 2022. URL: https://doi.org/10.3389/pore.2022.1610730, doi:10.3389/pore.2022.1610730. This article has 54 citations.

11. (jimbo2024pou2f3expressingsmallcell pages 27-32): Naoe Jimbo, Chiho Ohbayashi, Maiko Takeda, Tomomi Fujii, Suguru Mitsui, Ryuko Tsukamoto, Yugo Tanaka, Tomoo Itoh, and Yoshimasa Maniwa. Pou2f3-expressing small cell lung carcinoma and large cell neuroendocrine carcinoma show morphologic and phenotypic overlap. The American Journal of Surgical Pathology, 48:4-15, Oct 2024. URL: https://doi.org/10.1097/pas.0000000000002145, doi:10.1097/pas.0000000000002145. This article has 29 citations.

12. (yang2022pulmonarylargecell pages 7-8): Lan Yang, Ying Fan, and Hongyang Lu. Pulmonary large cell neuroendocrine carcinoma. Pathology and Oncology Research, Oct 2022. URL: https://doi.org/10.3389/pore.2022.1610730, doi:10.3389/pore.2022.1610730. This article has 54 citations.

13. (yang2022pulmonarylargecell pages 5-7): Lan Yang, Ying Fan, and Hongyang Lu. Pulmonary large cell neuroendocrine carcinoma. Pathology and Oncology Research, Oct 2022. URL: https://doi.org/10.3389/pore.2022.1610730, doi:10.3389/pore.2022.1610730. This article has 54 citations.

14. (serrano2024deltalikeligand3 pages 1-2): Alejandra G. Serrano, Pedro Rocha, Cibelle Freitas Lima, Allison Stewart, Bingnan Zhang, Lixia Diao, Junya Fujimoto, Robert J. Cardnell, Wei Lu, Khaja Khan, Beate Sable, Aaron R. Ellison, Ignacio I. Wistuba, Kyle F. Concannon, Daniel M. Halperin, Czerniak Bogdan, Kanishka Sircar, Miao Zhang, Kasey Cargill, Qi Wang, Ana Aparicio, Alexander Lazar, Sharia Hernandez, Jeannelyn Estrella, Preetha Ramalingam, Adel El-Naggar, Neda Kalhor, Carl M. Gay, Lauren Averett Byers, and Luisa M. Solis Soto. Delta-like ligand 3 (dll3) landscape in pulmonary and extra-pulmonary neuroendocrine neoplasms. NPJ Precision Oncology, Nov 2024. URL: https://doi.org/10.1038/s41698-024-00739-y, doi:10.1038/s41698-024-00739-y. This article has 46 citations and is from a peer-reviewed journal.

15. (robinson2023futuretherapeuticstrategies pages 14-14): Matthew D. Robinson, Daniel Livesey, Richard A. Hubner, Juan W. Valle, and Mairéad G. McNamara. Future therapeutic strategies in the treatment of extrapulmonary neuroendocrine carcinoma: a review. Therapeutic Advances in Medical Oncology, Jan 2023. URL: https://doi.org/10.1177/17588359231156870, doi:10.1177/17588359231156870. This article has 14 citations and is from a peer-reviewed journal.

16. (peddio2024dll3asa pages 1-3): Annarita Peddio, Erica Pietroluongo, Maria Rosaria Lamia, Angelo Luciano, Aldo Caltavituro, Roberto Buonaiuto, Giovanna Pecoraro, Pietro De Placido, Giovannella Palmieri, Roberto Bianco, Mario Giuliano, and Alberto Servetto. Dll3 as a potential diagnostic and therapeutic target in neuroendocrine neoplasms: a narrative review. Critical Reviews in Oncology/Hematology, 204:104524, Dec 2024. URL: https://doi.org/10.1016/j.critrevonc.2024.104524, doi:10.1016/j.critrevonc.2024.104524. This article has 29 citations.

17. (NCT05470595 chunk 2): A Single-arm Trial of Atezolizumab/Platinum/Etoposide for the Treatment of Advanced Large-cell Neuroendocrine Cancer of the Lung. Technische Universität Dresden. 2022. ClinicalTrials.gov Identifier: NCT05470595

18. (robinson2023futuretherapeuticstrategies pages 17-18): Matthew D. Robinson, Daniel Livesey, Richard A. Hubner, Juan W. Valle, and Mairéad G. McNamara. Future therapeutic strategies in the treatment of extrapulmonary neuroendocrine carcinoma: a review. Therapeutic Advances in Medical Oncology, Jan 2023. URL: https://doi.org/10.1177/17588359231156870, doi:10.1177/17588359231156870. This article has 14 citations and is from a peer-reviewed journal.

19. (recuero2023novelmousecell pages 1-2): Enrique Recuero, Sara Lázaro, Corina Lorz, Ana Belén Enguita, Ramón Garcia-Escudero, and Mirentxu Santos. Novel mouse cell lines and in vivo models for human high-grade neuroendocrine lung carcinoma, small cell lung carcinoma (sclc), and large cell neuroendocrine carcinoma (lcnec). International Journal of Molecular Sciences, 24(20):15284, Oct 2023. URL: https://doi.org/10.3390/ijms242015284, doi:10.3390/ijms242015284. This article has 8 citations.

20. (detjen2021modelsofgastroenteropancreatic pages 9-10): Katharina Detjen, Linda Hammerich, Burcin Özdirik, Münevver Demir, Bertram Wiedenmann, Frank Tacke, Henning Jann, and Christoph Roderburg. Models of gastroenteropancreatic neuroendocrine neoplasms: current status and future directions. Neuroendocrinology, 111:217-236, Jul 2021. URL: https://doi.org/10.1159/000509864, doi:10.1159/000509864. This article has 30 citations and is from a peer-reviewed journal.

21. (recuero2023novelmousecell pages 7-8): Enrique Recuero, Sara Lázaro, Corina Lorz, Ana Belén Enguita, Ramón Garcia-Escudero, and Mirentxu Santos. Novel mouse cell lines and in vivo models for human high-grade neuroendocrine lung carcinoma, small cell lung carcinoma (sclc), and large cell neuroendocrine carcinoma (lcnec). International Journal of Molecular Sciences, 24(20):15284, Oct 2023. URL: https://doi.org/10.3390/ijms242015284, doi:10.3390/ijms242015284. This article has 8 citations.

22. (jimbo2024pou2f3expressingsmallcell pages 21-27): Naoe Jimbo, Chiho Ohbayashi, Maiko Takeda, Tomomi Fujii, Suguru Mitsui, Ryuko Tsukamoto, Yugo Tanaka, Tomoo Itoh, and Yoshimasa Maniwa. Pou2f3-expressing small cell lung carcinoma and large cell neuroendocrine carcinoma show morphologic and phenotypic overlap. The American Journal of Surgical Pathology, 48:4-15, Oct 2024. URL: https://doi.org/10.1097/pas.0000000000002145, doi:10.1097/pas.0000000000002145. This article has 29 citations.

23. (jimbo2024pou2f3expressingsmallcell pages 9-15): Naoe Jimbo, Chiho Ohbayashi, Maiko Takeda, Tomomi Fujii, Suguru Mitsui, Ryuko Tsukamoto, Yugo Tanaka, Tomoo Itoh, and Yoshimasa Maniwa. Pou2f3-expressing small cell lung carcinoma and large cell neuroendocrine carcinoma show morphologic and phenotypic overlap. The American Journal of Surgical Pathology, 48:4-15, Oct 2024. URL: https://doi.org/10.1097/pas.0000000000002145, doi:10.1097/pas.0000000000002145. This article has 29 citations.

24. (serrano2024deltalikeligand3 pages 10-11): Alejandra G. Serrano, Pedro Rocha, Cibelle Freitas Lima, Allison Stewart, Bingnan Zhang, Lixia Diao, Junya Fujimoto, Robert J. Cardnell, Wei Lu, Khaja Khan, Beate Sable, Aaron R. Ellison, Ignacio I. Wistuba, Kyle F. Concannon, Daniel M. Halperin, Czerniak Bogdan, Kanishka Sircar, Miao Zhang, Kasey Cargill, Qi Wang, Ana Aparicio, Alexander Lazar, Sharia Hernandez, Jeannelyn Estrella, Preetha Ramalingam, Adel El-Naggar, Neda Kalhor, Carl M. Gay, Lauren Averett Byers, and Luisa M. Solis Soto. Delta-like ligand 3 (dll3) landscape in pulmonary and extra-pulmonary neuroendocrine neoplasms. NPJ Precision Oncology, Nov 2024. URL: https://doi.org/10.1038/s41698-024-00739-y, doi:10.1038/s41698-024-00739-y. This article has 46 citations and is from a peer-reviewed journal.

25. (NCT05680922 chunk 2): DLL3-Directed Chimeric Antigen Receptor T-cells in Subjects With Extensive Stage Small Cell Lung Cancer. Legend Biotech USA Inc. 2023. ClinicalTrials.gov Identifier: NCT05680922

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Term Validation

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• CL:0000450 (CL_0000450) (1 mention) - replaced by CL:0000136

29 of 30 terms resolved to a current term; the rest could not be looked up either way.

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.

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).

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:

"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.

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:

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

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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