What Are Gastrointestinal Stromal Tumors (GIST)?

Gastrointestinal stromal tumors (GISTs) are rare tumors that start in special cells found in the wall of the GI tract, called the interstitial cells of Cajal (ICCs). ICCs are part of the autonomic nervous system, and coordinate the automatic movements of the GI tract. ICCs are sometimes called the "pacemakers" of the GI tract because they send signals to the muscles of the digestive system, telling them to move food and liquid through the GI tract.

GISTs may occur anywhere along the length of the digestive tract from the esophagus to the anus. 

GIST is slightly more common in men. Although GISTs are most often diagnosed in people 50 years of age or older, they can occur in any age group. GIST appears to occur with increased frequency in patients with a history of neurofibromatosis (NF1 disease).

Approximately 50-70% of all GISTs develop in the stomach, while around 20-30% will arise in the small intestine. The rest arise in the esophagus, colon, and rectum. 

Most people who develop GIST have a mutation in a gene called c-kit, but researchers are not certain how the mutation causes the cancer and the cancer does not always manifest in the same way.