Question: are all gist tumors cancerous?
Answer: Gastrointestinal stromal tumors (GISTs) may be malignant (cancer) or benign (not cancer). They are most common in the stomach and small intestine but may be found anywhere in or near the GI tract. Some scientists believe that GISTs begin in cells called interstitial cells of Cajal (ICC), in the wall of the GI tract.