HeteroGeNETics: Neuroendocrine tumor genetics reflect their heterogeneous complex diversity

Neuroendocrine neoplasms (NENs) comprise a diverse group of malignancies arising across multiple anatomical sites and displaying remarkable biological and clinical heterogeneity. While advances in sequencing have identified recurrent genetic alterations in several NEN subtypes, these tumors remain largely characterized by a relatively low mutational burden and lack of dominant oncogenic drivers. Consequently, emerging evidence suggests that the molecular basis of neuroendocrine tumorigenesis extends beyond individual mutations and involves broader processes such as chromatin remodeling, telomere maintenance, epigenetic dysregulation and cellular plasticity. This review aims to summarize the current molecular landscape of pulmonary, gastro-enteropancreatic and thymic NENs, focusing on the biological pathways and cellular programs disrupted by recurrent genetic alterations unrelated to syndromes. We discuss how multi-omic studies have refined molecular classification and revealed common principles underlying neuroendocrine tumor development. Collectively, recent literature supports a shift from mutation-centered models toward a more integrated understanding of the complex biology and evolution of NENs.