Definition

A rare type of tumor that can form in the pancreas or in other parts of the gastrointestinal tract, including the stomach, small intestine, colon, rectum, and appendix. GEP-NETs usually form in cells that secrete hormones. Some of these tumors make extra amounts of hormones and other substances that may cause signs and symptoms of disease, including a condition called carcinoid syndrome. GEP-NETs may be benign (not cancer) or malignant (cancer). They are sometimes called carcinoid tumors or islet cell tumors. Also called gastroenteropancreatic neuroendocrine tumor.