Gastrointestinal stromal tumors (GISTs) are rare tumors that develop in the digestive tract. They are usually found in the stomach or small intestine, but can also occur in the esophagus, large intestine, rectum, or other parts of the digestive tract. GISTs are usually benign (non-cancerous) but can sometimes be malignant (cancerous). Treatment for GISTs may include surgery, chemotherapy, radiation therapy, or targeted therapy.