[Trends in gastroenteropancreatic neuroendocrine tumors]

Carcinoids were first reported approximately 100 years ago and proposed to be neuroendocrine tumors of hormonal origin some 50 years later. The first edition of the WHO classification included neuroendocrine tumors of the digestive organs and pancreas, but thereafter it was pointed that neuroendocrine cells are distributed throughout the body and thus that carcinoids occur in various other organs. The most recent edition of the WHO classification takes into account the occurrence of neuroendocrine tumors throughout the body. In addition, carcinoids were originally thought to be variants of a benign tumor type with a low malignancy rate, but thereafter metastases were observed. The term "neuroendocrine tumors" is now preferred instead of "carcinoids," and the malignant potential of such tumors is recognized. This paper reviews the classification and treatment of gastroenteropancreatic neuroendocrine tumors.