Gastrointestinal Stromal Tumors (GISTs)
Gastrointestinal stromal tumors (GISTs) are tumors of the GI tract derived from mesenchymal precursor cells in the gut wall. They result from mutations of a growth factor receptor gene, C-KIT. Some are caused by previous radiation therapy to the abdomen for other tumors.
Tumors are slow growing, and malignant potential varies from minimal to significant. Most (60 to 70%) occur in the stomach, 20 to 25% in the small bowel, and a small number in the esophagus, colon, and rectum. Average age at presentation is 50 to 60.
Symptoms of gastrointestinal stromal tumors vary with location but include bleeding, dyspepsia, and obstruction.
Diagnosis of gastrointestinal stromal tumors is usually by endoscopy, with biopsy and endoscopic ultrasonography for staging.
Treatment of gastrointestinal stromal tumors is surgical removal. The tyrosine kinase inhibitor imatinib can be used when tumors are positive for the KIT protein CD117; it is effective for patients with unresectable and/or metastatic malignant gastrointestinal stromal tumors and also as adjuvant treatment following resection in adults (1).
1. Dematteo RP, Ballman KV, Antonescu CR, et al: Adjuvant imatinib mesylate after resection of localised, primary gastrointestinal stromal tumour: A randomised, double-blind, placebo-controlled trial. Lancet 373(9669):1097–1104, 2009. doi: 10.1016/S0140-6736(09)60500-6. Clarification and additional information. Lancet 374(9688):450, 2009.