Gastrointestinal Stromal Tumors

Background: Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal tumors of the gastrointestinal tract. A relationship to the interstitial cells of Cajal (ICCs) has been proposed, and expression of CD117, the c-kit receptor present in ICCs, has been suggested as a marker for GISTs. Methods: The English literature has been reviewed with an emphasis on histogenetic features, especially the potential relationship of GISTs to ICCs. Results: GISTs are most common in the stomach (70%), followed by small intestine (20%), colon and rectum (5%), and esophagus (<5%). GISTs commonly have activating mutations in exon 11 (or rarely exon 9 and exon 13) of the KIT gene that encodes a tyrosine kinase receptor for the stem cell factor or mast cell growth factor. Conclusions: Malignant potential is best estimated by the simultaneous evaluation of several clinical parameters. The only absolute criterion for malignancy is tumor spread beyond the organ of origin at the time of diagnosis. The remarkable clinical response of tumors that express c-kit to treatment with the tyrosine kinase inhibitor STI571 is a triumph of molecular pharmacology. Those GISTs that express