Gastrointestinal Stromal Tumors Detailed Information

 Gastrointestinal stromal tumors (GIST) are a rare tumor of the gastrointestinal tract (1-3% of all gastrointestinal malignancies). GISTs can also initiate in the mesentery and omentum. Overall, GISTs are rare and rank a distant third in prevalence behind adenocarcinomas and lymphomas among the histologic types of gastrointestinal tract tumors. Gastrointestinal stromal tumors (GISTs) are approximately same in males and females. GISTs arise in 10-20 per one million people; one out of 3-4 is malignant.

This makes GIST the most common type of sarcoma, which comprises more than 70 types of cancer, but in all forms constitutes less than 1% of all cancer. In the United States annually has been estimated to be 5,000-6,000. Some families with hereditary GISTs have been described, most cases are sporadic. GISTs arise with a higher than expected frequency in patients with type 1 neurofibromatosis. GISTs are also a feature of the rare carney triad, which is observed predominantly in young women. This triad consists of epithelioid gastric stromal tumors, pulmonary chondromas, and extra-adrenal paragangliomas.

Tumors usually occur from the intestinal tract with the most common locate being the stomach, followed by the tiny intestine, and the colon/rectum with rare cases arising in the esophagus. There are also tumors that appear to arise in the membranous tissue lining the wall of the stomach (peritoneum) or in a fold of such membranous tissue. There are also case reports of tumors arising in the appendix and/or pancreas. These tumors most commonly present with abdominal pain, bleeding or signs of intestinal obstruction.They spread most commonly to sites within the abdominal cavity and to the liver.

While there are rare cases of spread to the lungs and bone. GIST results from a change in one of two genes, KIT or PDGFR, which leads to continued increase and division of tumor cells. Treatment is with surgery. Patients who have disease that has spread are treated with surgery when possible and with imatinib mesylate (Gleevec, Glivec), a tyrosine kinase inhibitor that inhibits the KIT or PDGFR responsible for tumor growth. Systemic chemotherapy trials for the treatment of GISTs have almost totally been associated with poor results.