| Knowledge-base field | Pulmonary LCNEC | Extrapulmonary LCNEC / poorly differentiated NEC | Ontology / identifier suggestions | Evidence |
|---|---|---|---|---|
| Definition and classification | Rare, high-grade pulmonary neuroendocrine carcinoma with large-cell, non-small-cell cytology, neuroendocrine architecture, extensive proliferation, necrosis, and neuroendocrine-marker expression. WHO reclassified it within pulmonary neuroendocrine carcinomas in 2015 and retained this concept in 2021. | Large-cell morphologic subtype of poorly differentiated neuroendocrine carcinoma arising outside the lung; reported in gastrointestinal, pancreatic, genitourinary, gynecologic, and other organs. It must be distinguished from well-differentiated grade-3 NET and mixed neuroendocrine–non-neuroendocrine neoplasms. | MONDO:0005057, large cell neuroendocrine carcinoma; MONDO:0003960, pulmonary large cell neuroendocrine carcinoma; category: neoplastic disease | (pqac-00000001, pqac-00000002, pqac-00000009) |
| Epidemiology | Approximately 0.3%–3% of lung cancers and 2.1%–3.5% of surgically resected lung cancers. Mean age is generally 60–70 years; patients are predominantly male and heavy smokers, with one synthesis reporting smoking histories in 92.8%. | Extremely rare and site-dependent; approximately 37% of all extrapulmonary NECs arise in the gastroenteropancreatic tract, followed by genitourinary and gynecologic sites. LCNEC-specific incidence by extrapulmonary organ is generally unavailable. | Adult onset; rare disease | (pqac-00000001, pqac-00000009) |
| Hallmark pathology | Organoid nests, peripheral palisading, trabeculae or rosettes; large polygonal cells with abundant cytoplasm, vesicular or coarse chromatin, and prominent nucleoli; extensive necrosis; more than 10 mitoses/2 mm², commonly 60–80/2 mm². | Similar poorly differentiated large-cell morphology, but organ-specific WHO criteria and associated non-neuroendocrine components must be assessed. Small-cell versus large-cell separation may have molecular and treatment relevance. | Suggested processes: cell proliferation, cell-cycle dysregulation, necrotic cell death | (pqac-00000008, pqac-00000013) |
| Molecular alterations and subtypes | Frequent somatic alterations include **TP53** (~82.3%), **RB1** (~39.1%), **KEAP1** (~20.9%), **STK11** (~18.2%), **KRAS** (~12.7%), and **EGFR** (~11.9%). Major groups are SCLC-like (**TP53/RB1** co-altered), NSCLC-like (often RB1-intact with **STK11/KEAP1/KRAS** alterations), and rare carcinoid-like/**MEN1** tumors. POU2F3-positive tuft-cell-like LCNEC represents approximately 12%–20%. | Alterations vary by organ: colorectal NEC is enriched for **KRAS**, gastric NEC may show **TERT** amplification, and biliary NEC may harbor **ARID1A** alterations. A 257-patient comparative cohort found potentially targetable alterations or biomarkers in 22.2% of GEP-NECs. These are acquired tumor drivers, not established germline causes. | Open Targets-supported genes: **TP53, RB1, SMARCA4, STK11, KEAP1, CDKN2A, BRAF, IDH2** | (pqac-00000000, pqac-00000008, pqac-00000013, pqac-00000020) |
| Major clinical phenotypes and metastases | Frequently incidental or nonspecific: cough, chest pain, hemoptysis, and respiratory symptoms. Common metastatic sites are liver, bone, brain, and adrenal gland. Brain metastases occur in about 19.2%–20% overall and up to 35% of stage-IV disease; neurologic deficits, raised intracranial pressure, and seizures may result. | Symptoms depend on the primary organ and metastatic burden. Most are nonfunctional carcinomas; local obstruction, bleeding, pain, weight loss, and liver or distant metastases are more typical than classic hormone syndromes. | Suggested HPO concepts: cough, hemoptysis, chest pain, dyspnea, seizure, increased intracranial pressure, and metastases to brain, liver, or bone | (pqac-00000001, pqac-00000002, pqac-00000003) |
| Diagnosis | Requires adequate tissue morphology plus at least one neuroendocrine marker: synaptophysin, chromogranin A, or CD56/NCAM1. INSM1 is positive in approximately 68%–91.3% and is a useful adjunct; TTF-1 is positive in about 54.8%. Ki-67 supports high-grade status but is not independently diagnostic. Small biopsies are prone to misclassification. | Requires organ-directed imaging and biopsy, confirmation of poor differentiation and large-cell morphology, neuroendocrine immunophenotyping, and exclusion of a pulmonary primary. Molecular or methylation profiling may help assign an unknown primary. | Diagnostic concepts: histopathology; immunohistochemistry; tumor next-generation sequencing; CT; MRI; FDG-PET | (pqac-00000001, pqac-00000003, pqac-00000008, pqac-00000010) |
| Differential diagnosis | SCLC, basaloid or poorly differentiated squamous carcinoma, adenocarcinoma with neuroendocrine-marker expression, carcinoid tumor, SMARCA4-deficient thoracic tumor, and metastatic extrapulmonary NEC. A coexisting NSCLC component supports combined LCNEC; an SCLC component is classified as combined SCLC. | Well-differentiated NET G3, small-cell NEC, organ-specific adenocarcinoma or squamous carcinoma, lymphoma, melanoma, and mixed neuroendocrine–non-neuroendocrine neoplasm. | Suggested approach: morphology integrated with broad epithelial, neuroendocrine, and organ-lineage IHC panels | (pqac-00000005, pqac-00000008, pqac-00000013, pqac-00000022) |
| Standard treatment | Resectable early disease: anatomic pulmonary resection with lymph-node staging, usually followed by platinum-based adjuvant chemotherapy because surgery alone has high recurrence. Advanced disease: platinum–etoposide is common; platinum–irinotecan or NSCLC-type platinum–gemcitabine/taxane may be considered, especially for RB1-intact/NSCLC-like tumors. Thoracic or brain radiotherapy is used selectively. | Localized disease may receive surgery or definitive chemoradiation. Advanced disease is generally treated with platinum–etoposide; no universally accepted second-line regimen exists. Treatment should incorporate primary site and actionable molecular alterations. | Suggested NCIt intervention concepts: surgical resection; cisplatin; carboplatin; etoposide; irinotecan; radiation therapy; stereotactic radiosurgery | (pqac-00000006, pqac-00000007, pqac-00000009, pqac-00000010) |
| Emerging targets and trials | Investigational chemoimmunotherapy includes atezolizumab–platinum–etoposide, phase II NCT05470595 (67 planned; active, not recruiting), and durvalumab–carboplatin–etoposide, phase II NCT06418087 (49 planned; recruiting). DLL3 is commonly expressed and is being explored with bispecific antibodies, radioligands, and cellular therapies; LCNEC-specific efficacy remains unproven. | Investigational approaches include dual checkpoint blockade, chemoimmunotherapy, DLL3 targeting, PRRT in receptor-positive disease, and genotype-matched **BRAF, KRAS G12C, ALK, NTRK**, or **RET** therapy. NCT06393816 evaluates durvalumab plus platinum–etoposide in NEC; NCT04079712 evaluates cabozantinib–nivolumab–ipilimumab in poorly differentiated NEC. | Suggested targets/interventions: DLL3; PD-1; PD-L1; CTLA-4; immune-checkpoint inhibitor therapy; molecularly targeted therapy | (pqac-00000010, pqac-00000011, pqac-00000012, pqac-00000016, pqac-00000018) |
| Prognosis | Aggressive, rapidly progressive, and prone to early relapse: reported recurrence is 63.9%–82% within one year and 91% within two years after surgery. Stage-I five-year survival is approximately 27%–67%. In a 2024 brain-metastasis cohort, median overall survival was 16 months from LCNEC diagnosis and 7 months after brain-metastasis diagnosis; synchronous versus metachronous brain metastasis yielded 11 versus 27 months. | Usually poor and governed by stage, primary site, differentiation, proliferation, and treatment response. Advanced extrapulmonary NEC studies commonly report median progression-free survival around 2–5 months and overall survival around 5–11 months, although LCNEC-only estimates are sparse. | Adverse features: advanced TNM stage, large tumor, distant or synchronous brain metastases; possible molecular modifiers include **KEAP1**, RB1 status, and immune infiltration | (pqac-00000003, pqac-00000006, pqac-00000012, pqac-00000015) |
| Prevention | No LCNEC-specific chemoprevention or vaccine exists. Tobacco avoidance and cessation are the most biologically supported primary-prevention measures. Eligible high-risk smokers may undergo standard low-dose CT lung-cancer screening, but there is no LCNEC-specific screening test. | No established organ-independent prevention or screening program. Apply standard prevention and screening for the organ of origin and modifiable carcinogenic exposures where relevant. Germline carrier or cascade screening is not routinely indicated because LCNEC is primarily sporadic and somatically driven. | Tobacco-use prevention; smoking cessation; low-dose computed tomography screening | (pqac-00000001, pqac-00000002) |
| Models | The 2023 **46LCNEC** murine line was derived from spontaneous CMV-QKO mouse LCNEC and forms syngeneic allografts in immunocompetent or immunodeficient mice. It retains the parental tumor’s LCNEC transcriptomic program and supports therapy and immunotherapy experiments, but murine and multifocal GEMMs do not fully capture human heterogeneity. | HROC57 is a BRAF-mutant colorectal LCNEC cell-line/PDX pair sensitive to etoposide, cisplatin, and 5-FU. NEC organoids and PDXs commonly retain **TP53/RB1/KRAS/BRAF** alterations; model numbers, standardization, and availability remain limited. | Species/model suggestions: *Mus musculus*; genetically engineered mouse model; syngeneic allograft; patient-derived xenograft; tumor organoid; cancer cell line | (pqac-00000019, pqac-00000023, pqac-00000024) |


*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.*