Carcinoid Tumor

What is a Carcinoid Tumor?

The neuroendocrine system is comprised of cells that are spread throughout several organ systems, including the lungs and digestive system. They are called neuroendocrine cells because they have characteristics of both nerve and endocrine cells. Nerve cells use electrical impulses to transmit signals. Endocrine cells, such as the thyroid and pancreas, make up glands that secrete hormones, such as thyroid hormone and insulin, which can be used to communicate with other organs. Tumors of the neuroendocrine system account for about 2% of all cancers and can be classified as either pancreatic endocrine tumors or carcinoid tumors. Approximately 12,000 cases of carcinoid tumor are diagnosed a year. They most commonly arise in the gastrointestinal system (esophagus, stomach, intestines) and are thought to regulate digestion by controlling digestive enzyme release and intestinal motility. About 30% of carcinoid tumors arise in the lungs. Because carcinoid tumors originate from hormone producing tissues, many of the side effects of carcinoid tumors can be linked to the inappropriate release of various compounds into the blood stream, which will be discussed later. Carcinoid tumors occur slightly more frequently in women than men with an overall rate of approximately 2.5 cases per 100,000 people. Carcinoid tumors also appear to be slightly higher in African Americans with 4.48 and 3.98 cases per 100,000 African American men and women, respectively. It is diagnosed most commonly between the ages of 50 to 70. Carcinoid tumors often do not cause symptoms and can be difficult to diagnose. Carcinoid tumors arise in three areas: the foregut, midgut and hindgut. The foregut includes the lungs and the stomach, the midgut is comprised of the small intestine, appendix, and the beginning of the large bowel (colon), and the hindgut is composed of the end of the large bowel, the rectum and the organs of the genitourinary tract (ovaries, testes). Recent data suggests that over the past 30 years the incidence of carcinoid tumors appears to be rising. Previously it was believed that these tumors were fairly benign, however, recent data suggest that they may be more aggressive than previously thought, with a 5-year survival rate of 67.2% for all carcinoid tumor sites.

Am I at Risk for Carcinoid Tumor?

Carcinoid tumors appear to be more common in women and African Americans. African Americans also tend to have a worse prognosis. There are medical conditions which are associated with carcinoid syndrome, including Multiple Endocrine Neoplasia (MEN) type I, Zollinger-Ellison Syndrome, atrophic gastritis, and ovarian teratomas. Recent studies suggest that the number of cases of carcinoid tumors diagnosed a year have been increasing by 6% per year, but it is unclear as to why this is occurring. Some studies have suggested that smoking may double the risk of carcinoid tumors in the small intestine. There does not appear to be an association between carcinoid tumors and diet.

How can I prevent carcinoid tumors?

Presently, there is no way to prevent carcinoid tumors. There may be an association between carcinoid tumors and smoking, hence not starting or quitting smoking may reduce the risk of developing carcinoid tumors.

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