Gastrointestinal stromal tumors (GISTs) are a type of tumor that occurs in the digestive system. The digestive system includes the esophagus, liver, stomach, gall bladder, large and small intestines, and rectum. The digestive system processes food to fuel the body and gets rid of waste. About half of GISTs occur in the stomach, but they can occur anywhere in the digestive system.

GISTs are rare. All GISTs are now considered potentially cancerous.

Digestive System
Digestive tract
GIST may occur anywhere in the digestive system.
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The cause of GISTs is not well understood.

Many people with GIST have a defect in a gene called c-kit. Usually, this gene is not active. However, in people with GIST, the c-kit gene often has a defect and is active, which enables the cells to grow and divide uncontrollably. This may explain why a GIST forms.

Theories about GISTs say that they begin in special cells of the digestive system. These cells are called interstitial cells of Cajal (ICCs). They send signals that tell the digestive system to contract, which moves food and liquid through the digestive system.