The Facts
Carcinoid syndrome is a pattern of symptoms that occurs in people who have carcinoid tumors. The symptoms are caused by hormones and chemicals produced by the carcinoid tumor and, in many cases, these symptoms are actually worse than the effects of the growth of the tumor itself.
Carcinoid tumors were first identified in Europe in the mid-1800s as a specific, distinct type of growth. The name carcinoid was first used in 1907 to classify them as a type of tumor that fit midway between malignant (cancerous) tumors and ones that were benign (non-malignant).
Carcinoid tumors can be widely distributed throughout the body, but are usually found in the digestive system (50% of cases) or lung (30% of cases). In children, carcinoid tumors are usually found in the appendix. Once the appendix is removed, the cancer is usually cured.
Carcinoid tumors produce too much of certain chemicals and hormones, and this can cause reactions in the body. One common chemical produced by carcinoid tumors is a hormone called serotonin. This hormone makes the blood vessels dilate (widen) and causes increased blood clotting, intestinal secretions, and motility (causing diarrhea).
Carcinoid tumors are rare, with 3 cases in every 100,000 people. They make up less than 1% of all cancers.