Gastrointestinal stromal tumor (GIST) is the most common mesenchymal tumor of the gastrointestinal tract. According to tumor size, GIST incidence varies from a highly prevalent tumor the "micro-GIST," which is <2 cm wide  and is estimated to occur in up to 22% of the general population, to a rare disease characterized by a tumor > 2 cm and with an annual incidence of about 15/1,000,000 . While the clinical relevance of microGIST is still under evaluation, at this point it is considered to be minimal. GISTs may develop from the esophagus to the rectum and are most common in the stomach (60-70% of the cases) followed by the small intestine (30%), and lastly by the rectum (<10%) . Although no GIST > 2 cm can be considered benign, the risk of local relapse and metastasis varies according to tumor size and site of origin, and the number of mitoses evaluated on 50 microscopic high-power fields. This risk stratification proposed by Miettinen and Lasota  is widely used as a prognosticator after complete surgery, which is still the mainstay of therapy. However, despite complete surgical removal of the tumor, the 50% relapse rate is surprisingly consistent throughout different large series . Relapse may occur locally but mostly involves the peritoneum and liver. Patients with relapse not amenable to surgery previously died within 12 months  due to the chemoresistance of GIST, in which the response rate to chemotherapy is <5% .
ASJC Scopus subject areas
- Biochemistry, Genetics and Molecular Biology(all)