Gastroenteropancreatic Neuroendocrine Tumors: Does Tumor Location Affect Prognosis?

Background: Gastroenteropancreatic neuroendocrine tumors (GEP-NETs) are rare entities. Generally, they can be localized anywhere in the gastrointestinal or hepatobiliary tract. The purpose of our study is to evaluate the effect of tumor location on prognosis in patients with GEP-NET undergoing surgery. Our secondary objective is to examine other factors affecting the prognosis of patients with GEP-NET. Methods: We retrospectively analyzed data from 30 patients with GEP-NET who underwent surgery in the General Surgery Clinic between 2012 and 2022. The gNET group (n = 18) included tumors located in the gastrointestinal tract, while the pNET group (n = 12) included tumors located in the hepatopancreatobiliary system. Surgical, laboratory, radiological, and pathological findings of the patients, as well as follow-up outcomes were recorded and statistically analyzed. Results: In subgroup comparison, tumor size was found to be larger in the pNET group (P = 0.002). The statistical analysis of recurrence (16.7% versus 33.3%) and mortality rates (16.7% versus 41.7%) between the subgroups (P= 0.329 and P = 0.210, respectively) did not reveal a significant difference. When all patients were evaluated, it was observed that advanced age, presence of carcinoma diagnosis, higher tumor grade, advanced TNM stage, larger tumor size, presence of lymphovascular or perineural invasion, elevated mitotic index, higher Ki-67 index, and having received adjuvant therapy increased the rates of recurrence and mortality. Conclusion: There was no statistically significant difference in survival outcomes between the GEP-NET groups located in the gastrointestinal tract and the hepatopancreatobiliary system.