High-grade gastroenteropancreatic neuroendocrine neoplasms. Modern classification, diagnostics and treatment

Poorly differentiated gastroenteropancreatic neuroendocrine neoplasms (GEP NENs) are rare malignancies, most of which are characterized by aggressiveness, a tendency to rapid metastasis and an unfavorable prognosis even when localized. In 2017 World Health Organization (WHO) updated classification of GEP NENs and recognized the category of well-differentiated pancreatic NET G3, associated with Ki-67 index usually over 20%. The upper level of Ki-67 is not defined. Usually it is 55%. Highgrade poorly differentiated pancreatic NENs are defined as pancreatic neuroendocrine carcinomas (panNECs). Although the NET G3 category is recognized for pancreatic neuroendocrine neoplasms only, many specialists consider it reasonable to apply this term to all well-differentiated GEP NETs with Ki-67 index in the 20 to 55 percent range. Clinical behavior and therapeutic approaches for advanced GEP NECs and NETs G3 are different. Standard palliative chemotherapy for GEP NECs consists of cisplatin or carboplatin combined with etoposide...