A gastrointestinal carcinoid tumor is cancer that forms in the lining of the gastrointestinal tract.

The gastrointestinal tract includes the stomach, small intestine, and large intestine. These organs are part of the digestive system, which processes nutrients (vitamins, minerals, carbohydrates, fats, proteins, and water) in foods that are eaten and helps pass waste material out of the body. Gastrointestinal carcinoid tumors develop from a certain type of hormone -making cell in the lining of the gastrointestinal tract. These cells produce hormones that help regulate digestive juices and the muscles used in moving food through the stomach and intestines. A gastrointestinal carcinoid tumor may also produce hormones. Carcinoid tumors that start in the rectum (the last several inches of the large intestine) usually do not produce hormones.

Gastrointestinal carcinoid tumors grow slowly. Most of them occur in the appendix (an organ attached to the large intestine), small intestine, and rectum. It is common for more than one tumor to develop in the small intestine. Having a carcinoid tumor increases a person's chance of getting other cancers in the digestive system, either at the same time or later.

Recurrent Gastrointestinal Carcinoid Tumors

A recurrent gastrointestinal carcinoid tumor is a tumor that has recurred (come back) after it has been treated. The tumor may come back in the stomach or intestines or in other parts of the body.