Gastrointestinal stromal tumors, also known as GISTs, are the most common type of mesenchymal tumors found in the gastrointestinal tract.
They are tumors of connective tissue that form in the stomach, esophagus and small intestine. Smaller GISTs can be benign, but it is important to seek proper diagnosis to be certain.
Larger tumors can disseminate to the liver, peritoneal cavity and the omentum. 50% – 80% of GISTs occur because of a mutated gene called c-kit.
Signs & Symptoms
Signs and symptoms of GISTs may include having trouble swallowing, bleeding in the gastrointestinal tract and a history of abdominal pain. Sometimes, though rarely, there will be an obstruction caused by the tumor growth. Unfortunately, tumors are usually large by the time they are discovered and diagnosed.
Blood tests and CT scanning may initially indicate to doctors that a GIST is present. If that is their suspicion they will perform a biopsy. GIST tumors generally grow in the intestine wall or the bowel wall. The tissue from the biopsy is tested for CD117, DOG-1, a sequencing of Kit, and PDGFRA – all of which indicate the presence of a GIST.
Treatment for GISTs depends on the size, location and diagnosis of the tumor. In general the tumor can be treated with minimally invasive laparoscopic abdominal surgery. GIST tumors used to be extremely resistant to chemotherapy; however, recently it was discovered that use of the drug imatinib leads to an increased survival rate in patients with inoperable tumors. Imatinib is a drug that was originally marketed for treating chronic myelogenous leukemia.
The prognosis for patients with GISTs varies greatly depending on the size, location and stage of the tumor. Patients with smaller benign tumors that can be removed surgically have a very high survival rate.
The use of imatinib in treating GISTs has greatly increased survival rates in patients with advanced GISTs. In the past it was estimated that patients with more advanced GISTs had a survival rate of approximately two years, but with the use of imatinib this has seen a 75 – 80% increase.