[Clinicopathological features and outcome of gastroenteropancreatic high-grade (WHO G3) neuroendocrine tumors: a study of 60 cases].

Objective: To investigate the clinicopathological features and outcome of gastroenteropancreatic high-grade neuroendocrine tumors. Methods: A total of 60 gastroenteropancreatic high-grade neuroendocrine tumors were collected from January 1st, 2013 to December 31th, 2018 at Fudan University Shanghai Cancer Center, with available pathology databases and clinic follow-up information. At the same time, 157 cases of gastrointestinal pancreatic neuroendocrine neoplasm (NEN) diagnosed at the hospital in 2018 were collected and the incidence of NEN at all grades was compared. Results: There were 32 males and 28 females, aged 13-80 years (mean 54 years). Pancreas primary was the most common (48%, 29/60). Nodal metastatic rate was 9/16 and distant metastatic rate was 41%(18/44). Liver was the most common site of metastasis. Among all the gastroenteropancreatic neuroendocrine neoplasms diagnosed in the hospital in 2018, the incidence of high-grade neuroendocrine tumors was the lowest (7%, 11/157). High-grade neuroendocrine tumors had typical pathologic features of well-differentiated/moderate neuroendocrine tumors, but with significant differences in mitotic rates. By immunohistochemical staining, most of the tumors expressed neuroendocrine markers and somatostatin receptor 2 was positive in 60% (12/20) of the cases. The average Ki-67 index was 30%-40%, and there was significant difference between cases (18%-80%). The overall survival of high-grade neuroendocrine tumors was 43 months, and the disease-free survival was 12 months. Conclusions: High-grade neuroendocrine tumor is a rare group of neuroendocrine tumors, with unique clinicopathological features and good prognosis. Pathological classification and grading of gastroenteropancreatic neuroendocrine neoplasms can help clinicians to select appropriate treatment and accurately evaluate prognosis.