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Gastrointestinal Complications (PDQ®)

General Information

The gastrointestinal (GI) tract is 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. The GI tract includes the stomach and intestines (bowels). The stomach is a J-shaped organ in the upper abdomen. Food moves from the throat to the stomach through a hollow, muscular tube called the esophagus. After leaving the stomach, partly-digested food passes into the small intestine and then into the large intestine. The colon (large bowel) is the first part of the large intestine and is about 5 feet long. Together, the rectum and anal canal make up the last part of the large intestine and are 6-8 inches long. The anal canal ends at the anus (the opening of the large intestine to the outside of the body).

Gastrointestinal (digestive) system anatomy; shows esophagus, liver, stomach, colon, small intestine, rectum, and anus.
Anatomy of the lower digestive system, showing the colon and other organs.


GI complications are common in cancer patients. Complications are medical problems that occur during a disease, or after a procedure or treatment. They may be caused by the disease, procedure, or treatment, or may have other causes. This summary describes the following GI complications and their causes and treatments:

This summary is about GI complications in adults with cancer. Treatment of GI complications in children is different than treatment for adults.

  • Updated: December 11, 2014