Management of advanced high grade gastro-enteropancreatic neuroendocrine neoplasms (GEP-NENs): comprehensive review of the current literature

The classification and management of neuroendocrine neoplasms (NENs) arising in the tubular gastrointestinal (GI) tract and pancreas have significantly evolved over the last decades. In the latest WHO classification published in 2022, NEN are separated regardless of their primary origin into two main groups: well-differentiated neuroendocrine tumors (NETs) and poorly differentiated neuroendocrine carcinomas (NECs). The substantial changes in grading system changed the definition of grade 3 to include high grade well differentiated NETs (G3-NETs), and poorly differentiated NECs (-NECs). Although, these two subgroups are considered high grades with Ki-67 >20%, they have different genomic profiles, prognosis and clinical behavior which critically influence their treatment strategies. The available clinical trial data to guide therapy of these high-grade subgroups are extremely limited which impact their management. In this review, we will summarize the current advances in the multidisciplinary approach for management of high grade GEP-NENs including G3-NETs and NECs.