Neuroendocrine tumors (NETs) are rare and originate from specialized cells called neuroendocrine cells. These cells, which have features like nerve cells and hormone-producing cells, release hormones into the blood in response to signals from the nervous system. Neuroendocrine tumors can occur throughout the body, but primary sites include the gastrointestinal tract, pancreas, rectum, lungs, and appendix. The majority of neuroendocrine tumors can be divided into two classes: carcinoid and pancreatic neuroendocrine tumors. Pheochromocytoma is a rare form of neuroendocrine tumor.
Over 170,000 people in the U.S. are living with neuroendocrine cancers. It is estimated that over 12,000 people are diagnosed each year, and the number of those diagnosed is increasing by more than five percent annually. The majority of all NET patients are initially misdiagnosed, and the time from onset of symptoms to proper diagnosis often exceeds five years. Many physicians and specialists are not aware of current diagnostic and treatment options. Too often, doctors still believe NETS are benign, slow growing, and do not metastasize. The most prevalent symptoms are diarrhea, constipation, flushing, abdominal pain, wheezing, heart palpitations, and blood pressure fluctuations.
Carcinoid commonly refers to neuroendocrine tumors that originate in the gastrointestinal (GI) tract, lungs, appendix and thymus, although they can also occur in the lymph nodes, brain, bone, gonads (ovaries and testes) and skin. Carcinoid tumors are usually indolent (slow-growing) by nature and develop over the course of many years, however, aggressive, fast-growing forms of carcinoid cancer also exist. For a general guide to carcinoid tumors, including symptoms, diagnosis, and treatment options, please refer to our Carcinoid Tumors page.
Pancreatic Neuroendocrine Tumors
Neuroendocrine tumors that arise in the pancreas are called pancreatic neuroendocrine tumors or islet cell tumors. Pancreatic neuroendocrine tumors can include: nonfunctional tumors, insulinomas, glucagonomas, gastrinomas, VIPomas, somatostatinomas, GHRHomas, and other less frequent tumors. Pancreatic neuroendocrine tumors are usually indolent (slow-growing) by nature and develop over the course of many years, however, aggressive, fast growing pancreatic neuroendocrine tumors exist. For a general guide to Pancreatic NETs, including symptoms, diagnosis, and treatment options, please refer to our Pancreatic NETs page.
Pheochromocytoma is a rare form of neuroendocrine tumor that usually develops in the adrenal gland, but can also arise in other parts of the body. Pheochromocytomas produce excess amounts of adrenalin and related hormones, which are the “fight-or-flight” hormones usually released by the adrenal glands in response to stress. These hormones can cause a person to have elevated blood pressure (hypertension) and an increased heart rate. Patients with pheochromocytomas often have unusually severe or unexplained hypertension. Pheochromocytomas are also sometimes diagnosed when a tumor on the adrenal gland is observed during CT scans or other imaging performed for unrelated medical conditions.