Classification of Gastroenteropancreatic Neuroendocrine Tumors

Gastroenteropancreatic neuroendocrine tumors are a heterogeneous group of tumors. There are several classification systems, and all of them have been validated.The article aims to summarize the existing classification systems of gastroenteropancreatic neuroendocrine tumors.A critical evaluation was based on the data available from existing studies.The classification of the European neuroendocrine tumor society is the one with the clinical benefits.The lack of unified classification systems creates incomplete epidemiologic data, leading to confusion among pathologists and clinicians.