In medical oncology, gastrointestinal stromal tumors (GIST) are a rare tumor of the gastrointestinal tract (1-3% of all gastrointestinal malignancies).

GIST is a form of connective tissue cancer, or sarcoma. GISTs are therefore non-epithelial tumors, separate from more common forms of bowel cancer. 70% occur in the stomach, 20% in the small intestine and less than 10% in the esophagus. Small tumors are generally benign, especially when cell division rate is slow, but large tumors disseminate to the liver, omentum and peritoneal cavity. They rarely occur in other abdominal organs.

CD117

• a sensitive marker for gastrointestinal stromal tumors that is more specific than CD34. PMID: 9720500