Gastrointestinal neuroendocrine tumors

Abstract

Neuroendocrine tumors (NETs) are a genetically diverse group of malignancies that have neuroendocrine differentiation and occurs most often in the digestive system. Digestive system-associated NETs are classified into gastrointestinal (GI)-NETs and pancreatic NETs. GI-NET was formerly known as carcinoid which causes carcinoid syndrome as the main presentations. Because the symptoms are not specific, it is often misdiagnosed as other diseases. The current diagnostic tools include 24-hour urinary excretion of 5-hydroxyindoleacetic acid, serum chromogranin A, image, endoscopy, and somatostatin receptor scintigraphy. In 2017, the World Health Organization (WHO) updated the classifications of all gastroenteropancreatic NETs based upon tumor cell differentiation, mitotic count and proliferative index (Ki-67). The treatment strategies are conducted according to tumor size, tumor cell differentiation, proliferation, and liver metastasis or not. This review article summaries the current knowledge of GI-NET, including the epidemiology, clinical presentation, diagnosis, staging and updated treatment. Clinicians will leam more about GI-NET from this paper to increase the early diagnosis rate which leads toproper management followed by improved overall survival.