A carcinoid tumor is a type of slow-growing cancer that typically arises in the gastrointestinal tract, particularly in the small intestine, but can also occur in other areas like the lungs. These tumors develop from neuroendocrine cells, which produce hormones that can affect various bodily functions. Symptoms of carcinoid tumors may include abdominal pain, flushing of the skin, and diarrhea, often due to hormone release. Diagnosis usually involves imaging tests and blood tests to measure hormone levels. Treatment options may include surgery, medication, and sometimes radiation therapy, depending on the tumor's location and stage.