Gastrointestinal stromal tumors (GISTs) are sarcomas (cancerous tumors of connective tissue) that develop from mesenchymal precursor cells within the wall of the esophagus, stomach, or intestines. GISTs are the most common type of sarcoma in the digestive tract.
Most GISTs are caused by a mutation in a gene called C-KIT that controls the growth of cells, and some are caused by a mutation in a gene called PDGFRB that provides instructions for making a certain protein.
GISTs may develop in people with a genetic syndrome. One common syndrome is neurofibromatosis type 1.
About half of these tumors occur in the stomach, some occur in the small intestine, and a small percentage occurs in the esophagus, colon, and rectum.
The average age at diagnosis is 50 to 60. People who have had radiation therapy to the abdomen for the treatment of other tumors can develop gastrointestinal stromal tumors at a later time.
These tumors usually grow slowly, but some can grow more rapidly and spread to other sites (metastasize).
Symptoms of GISTs
Symptoms of GISTs depend on the location of the tumor but include abdominal pain, bleeding, indigestion, and a feeling of fullness after eating a small meal. Nausea and vomiting can occur if the tumor has grown large enough to block the digestive tract.
Diagnosis of GISTs
Endoscopy
Imaging tests
A doctor may use an endoscope (a flexible viewing tube) to locate the tumor and do a biopsy (remove a tissue sample for examination under a microscope).
To determine whether the cancer has spread to other organs, doctors do a computed tomography (CT) scan of the chest, abdomen, and pelvis and endoscopic ultrasonography (in which an ultrasound probe placed on the tip of the endoscope shows the lining of the digestive tract more clearly than many other tests).
Treatment of GISTs
Surgical removal
Doctors surgically remove GISTs.
If the cancer has spread or cannot be treated surgically, doctors often treat it with the chemotherapy agent imatinib. If the cancer has spread or cannot be treated surgically, doctors often treat it with the chemotherapy agent imatinib.Imatinib is also frequently given before surgery to shrink some tumors and make surgery possible or easier. If imatinib does not help, doctors may give other chemotherapy agents such as sunitinib and regorafenib. does not help, doctors may give other chemotherapy agents such as sunitinib and regorafenib.
Another medication called avapritinib can be given to people who have GISTs that are caused by a genetic mutation called PDGFRA exon 18.Another medication called avapritinib can be given to people who have GISTs that are caused by a genetic mutation called PDGFRA exon 18.
