Neuroendocrine tumors are those that begin in neuroendocrine cells, cells that have traits similar to both nerve cells and hormone-producing cells. Neuroendocrine tumors are rare and can develop anywhere that hormone-producing cells are present. Most neuroendocrine tumors develop in the digestive tract or pancreas. Some develop in the lung or the reproductive or urinary systems.
The digestive tract consists of the mouth, throat, esophagus, stomach, small intestine, large intestine (including the appendix), rectum, and anus. The function of the digestive tract is to take in food, break it down, extract nutrients, absorb them into the body, and dispose of waste. Stomach acid and various digestive secretions from the liver and pancreas aid this process.
Gastrointestinal neuroendocrine tumors most often arise in the small intestine, large intestine, and appendix. They are usually slow-growing, may secrete hormones that affect bowel function, and may be noncancerous (benign) or cancerous (malignant).
The pancreas is an organ located in the upper part of the abdomen. The pancreas produces digestive juices (including enzymes) that are secreted into the digestive tract. The pancreas contains different types of cells. Those called islet cells produce several types of hormones, including insulin, which helps control blood sugar.
Pancreatic neuroendocrine tumors are tumors that arise from the islet cells. These tumors may or may not secrete hormones themselves and may be cancerous or noncancerous.
There are 2 types of gastrointestinal and pancreatic neuroendocrine tumors:
Functioning
Nonfunctioning
Nonfunctioning tumors do not secrete hormones and are not cancerous. These tumors may cause symptoms by blocking the biliary tract or small intestine, by bleeding into the gastrointestinal tract, or by causing a mass in the abdomen.
Functioning tumors secrete large amounts of a particular hormone, causing various symptoms or other physical changes. Some functioning tumors are cancerous. The hormones that may be secreted and their tumor type include
Insulin (insulinoma)
Gastrin (gastrinoma)
Glucagon (glucagonoma)
Vasoactive intestinal peptide (vipoma)
Excess secretion of these hormones can also occur in a disorder called multiple endocrine neoplasia.
Treatment of Gastrointestinal and Pancreatic Neuroendocrine Tumors
Surgery
Medications that block hormone effects
Sometimes chemotherapy
Most gastrointestinal and pancreatic neuroendocrine tumors, whether functioning or nonfunctioning, are treated with surgical removal. However, for some small, nonfunctioning tumors, doctors may monitor them instead of removing them surgically.
People who have a cancerous tumor that has spread (metastasized) are usually treated with chemotherapy.
