Molecular Subtypes of Neuroendocrine Carcinoma: From Chaos to Consensus

Neuroendocrine carcinomas (NECs) represent a notoriously aggressive family of lethal malignancies arising across diverse anatomical sites. Molecular subtyping based on key transcription factors ASCL1, NEUROD1, POU2F3, and YAP1 has significantly advanced understanding of tumor heterogeneity in small cell lung cancer (SCLC). Beyond SCLC, extrapulmonary NECs demonstrate analogous heterogeneity, similarly governed by these transcriptional determinants. Recent studies have further identified a fifth subtype driven by the lineage-specifying factor HNF4A. This review aims to propose a unified pan-NEC classification framework for consistent molecular subtyping across pulmonary, gastro-entero-pancreatic (GEP), and genitourinary systems. We delineate the distinct lineage hallmarks of the ANHPY subtypes (neuroendocrine, neuronal, GEP-like, tuft-like, and epithelial–mesenchymal transition phenotypes) and explore their connections to defining mechanisms, genetic alterations, clinicopathological features, and therapeutic vulnerabilities. This unified framework serves as a molecular roadmap for precise NEC research and management.