Abstract

Objective: Neuroendocrine neoplasms (NEN) are frequently located in the lung and gastroenteropancreatic (GEP)

system organs. Neuroendocrine carcinoma (NEC) constitutes 5% of GEP NENs and has a very high malignancy

potential. In this study, it is aimed to determine a new threshold value in addition to the 20% Ki-67 proliferation

index that was specified as a threshold value for predicting survival in patients with grade (G) 3 tumors according

to World Health Organization (WHO) 2010 classification.

Method: Demographic, clinicopathologic features and survival rates of 34 patients diagnosed with GEP NEC

between 2008-2015 in İzmir Katip Celebi University Atatürk Training and Research Hospital Medical Pathology

Clinic were evaluated retrospectively.

Results: Most of the 34 (76.5%) cases were male and the average age was 63.9 years. Median survival rates were

15, and 7 months in patients with Ki-67 indexes of ≤65% and >65%, respectively (p=0.232).

Conclusion: Recent studies have shown heterogeneity of high-grade NENs, identified as NEC and foreseen their

subdivision into biological subgroups. The researchers suggest that the NECs should be divided into two categories

as patients with Ki-67 indexes of 20-55% and >55%. In our study, the most significant difference in survival rates

was observed when 65% was selected as threshold value for Ki-67 index which supports the results of other studies in the literature. Since the number of our cases is limited and it is a single-center study, the findings obtained

needs to be further investigated in studies with greater number of case series.