Neuroendocrine tumors are a relatively uncommon type of tumor. It was previously thought to be a class of slow-growing carcinoid tumors. After nearly a century of research, it was recognized that from the initial vague carcinoid tumors developed to the present day, it is clear that they originate from tumors of the neuroendocrine system. It has also been further recognized that these tumors are composed of a variety of different types of cells of different embryonic origins with common characteristics, and can synthesize a variety of bioactive amines, peptides and other substances such as neurotransmitters, hormones and paracrine regulators acting in the tissue. The incidence of this disease was previously thought to be low, but in recent years there has been a significant increase, and the current statistical incidence is about 5.25/100,000. Etiology Most neuroendocrine tumors are disseminated, and their exact etiology is not known. However, a small proportion of neuroendocrine tumors are genetically related, involving deletions and mutations of some genes, such as multiple endocrine adenomas (mutipleendocrineneoplasia, MEN) and the vonHippel-lindausyndrome (VHLsyndrome). Clinical manifestations According to whether the tumor has hormone-secreting function and the presence or absence of hormone-induced clinical symptoms, neuroendocrine tumors are divided into two categories: non-functional (about 80%) and functional (about 20%). Non-functional gastroenteropancreatic neuroendocrine tumors mainly manifest non-specific gastrointestinal symptoms or local occupying symptoms of the tumor, such as progressive dysphagia, abdominal pain, bloating, diarrhea, abdominal mass, jaundice or black stool, etc. Functional gastroenteropancreatic neuroendocrine tumors mainly manifest clinical symptoms related to the secretion of biologically active hormones by the tumor, such as skin flushing, sweating, asthma, diarrhea, hypoglycemia, refractory peptic ulcers, and peptic ulcer. Functional gastroenteropancreatic neuroendocrine tumors are mainly pancreatic neuroendocrine tumors, including insulinoma, growth inhibitor tumor, glucagon tumor, gastrinoma, etc.