Gastrointestinal stromal tumors: Current diagnosis, biologic behavior, andmanagement

Gastrointestinal stromal tumors (GIST) are rare tumors of the gastrointesti nal (GI) tract that arise from primitive mesenchymal cells. GISTs occur thr oughout the GI tract but are usually located in the stomach and small intes tine. The majority of GISTs are immunohistochemically positive for c-kit pr otein (CD117) and CD34. GISTs express a heterogeneous clinical course not e asily predicted by standard pathological means. The most important prognost ic factors are size > 5 cm, tumor necrosis, infiltration and metastasis to other sites, mitotic count > 1-5 per 10 high-powered fields, and most recen tly, mutation in the c-kit gene. Surgical resection remains the mainstay of treatment, as chemotherapy and radiation are ineffective. Long-term follow -up is imperative, as recurrence rates are high.