While recent therapeutic developments have increasingly focused on targeted agents and radiolabeled therapies, cytotoxic chemotherapy remains a vital treatment option for specific neuroendocrine tumor phenotypes, particularly pNETs with high tumor burden, high-grade well-differentiated tumors (Ki-67 index between 20% and 55%), and poorly differentiated neuroendocrine carcinomas (NECs). This evidence concerns the gene MKI67 and neuroendocrine carcinoma.