Carcinoid tumors are rare, slow-growing cancers that usually start in the lining of the digestive tract or in the lungs. Because they grow slowly and don't produce symptoms in the early stages, the average age of people diagnosed with digestive or lung carcinoids is about 60. In later stages the tumors sometimes produce hormones that can cause carcinoid syndrome. The syndrome causes flushing of the face and upper chest, diarrhea, and trouble breathing. Surgery is the main treatment for carcinoid tumors. If they haven't spread to other parts of the body, surgery can cure the cancer.