Gastrointestinal carcinoid tumors are a rare form of cancer that develop in the gastrointestinal tract, which includes the stomach, small intestine and large intestine.

Gastrointestinal carcinoid tumors grow slowly and are highly treatable when caught at the earliest stages. However, patients with these tumors usually do not experience symptoms until the cancer has spread (metastasized), making it more difficult to detect these tumors until they have become more advanced.

The location and size of the tumor play a large role in determining whether or not it will spread. Very small tumors – less than 1 centimeter (about 1/2 inch) – usually do not spread, while larger tumors do. Because carcinoid tumors grow so slowly, patients whose cancer has spread may live for extended periods of time with the tumor.

Although gastrointestinal carcinoid tumors do not typically produce symptoms in their early stages, they sometimes produce mild abdominal pain if the tumors cause a bending or blockage of the intestines.

Early-stage gastrointestinal carcinoid tumors are sometimes discovered when a patient is being examined for another medical condition. However, a physician may suspect this type of tumor in patients who report persistent abdominal pain. Various imaging tests may be used to help diagnose this condition.