[Issues on classification of gastric neuroendocrine tumors]

A comparative analysis of available classifications of gastric neuroendocrine tumors was performed. It was showed that there were many contradictions regarding the issues of termi- nology and, in particular, criteria for determining the degree of differentiation of these tumors that significantly influenced on the choice of methods of treatment. There were unclearly marked symptoms of benign tumors, treatment of which could be conducted by endoscopy removal. There was absent the category of high- and moderately differentiated neuroendocrine tumors that metastasized by lymph and blood. Malignant tumors were represented by just low-differentiated malignancies although now many researchers noted the heterogeneity of this group and a different response to therapeutic agents. Up to now there were no standard methods for determining the pro- liferative level because any discrepancies between a number of mitoses and Ki67 index might be. Proliferative activity in tumor itself was often heterogeneous and it was necessary to select a specific point in tumor to determine its grade. Despite a proof of endodermal origin and the presence of combined tumors with epithelial component (mucocarcinoid, adenoneuroendocrine, amphicrine carcinoma) gastric neuroendocrine tumors were considered as a separate group in contrast to such standard symbols in pathology as adenomas and carcinomas. Thus it is necessary to accumulate further material for the standardization of nomenclature and more accurate determina- tion of malignant potential of tumors with the aim of studying the effect of various methods of treatment.