Ernest H. Rosenbaum, MD, Malin Dollinger, MD, and Larry K. Kvols, MD
Adapted for the Canadian edition by Sheldon Fine, MD
Carcinoid tumors are unusual cancers. Although they can develop in other organs, especially the lung, they generally arise in the intestinal tract, including the stomach, small bowel, appendix and rectum. They are the most common tumors of the appendix, occurring in one out of every 300 appendectomies. They make up 30 percent of small bowel tumors but less than 2 percent of all gastrointestinal malignancies.
In their early stages, carcinoid tumors are highly treatable and often curable. They are usually slow growing and behave like benign tumors. The risk of metastasis is related to the size of the primary tumor .
Carcinoids may occur in multiple sites (about 20 percent have multiple tumors) and, except for those of rectal origin, may produce an endocrine substance called serotonin. In most cases there are no symptoms, so many carcinoid tumors are discovered incidentally during abdominal operations performed for other reasons. The survival of most people with carcinoid tumors is quite good, although symptoms may develop when the tumor cannot be removed, when it recurs after treatment or when there is metastatic disease.
