A slow-growing cancer that can begin in the stomach, appendix, small intestine, colon, rectum or lung. The cancer can release hormones that cause symptoms, such as diarrhea and skin flushing.

Symptoms often don't appear until late in the disease and are vague. Examples include diarrhea and skin flushing.

Treatment includes surgery, chemotherapy, targeted therapy and medicines to control the excess hormones made by the cancer.