Gastrointestinal stromal tumors (GISTs) are sarcomas (cancerous tumors of connective tissue) that develop from mesenchymal precursor cells within the wall of the esophagus Throat and Esophagus The throat (pharynx) lies behind and below the mouth. When food and fluids leave the mouth, they pass through the throat. Swallowing of food and fluids begins voluntarily and continues automatically... read more , stomach Stomach The stomach is a large, bean-shaped, hollow muscular organ consisting of four regions: Cardia Fundus Body Antrum read more , 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 Neurofibromatosis Neurofibromatosis is a group of genetic disorders in which many soft, fleshy growths of nerve tissue (neurofibromas) form under the skin and in other parts of the body, and flat spots that are... read more .
About half of these tumors occur in the stomach, some occur in the small intestine Small Intestine The duodenum is the first segment of the small intestine, and the stomach releases food into it. Food enters the duodenum through the pyloric sphincter in amounts that the small intestine can... read more , and a small percentage occurs in the esophagus, colon Large Intestine The large intestine consists of the Cecum and ascending (right) colon Transverse colon Descending (left) colon Sigmoid colon (which is connected to the rectum) read more , and rectum Rectum and Anus The rectum is a chamber that begins at the end of the large intestine, immediately following the sigmoid colon, and ends at the anus ( see also Overview of the Anus and Rectum). Ordinarily,... read more .
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
A doctor may use an endoscope Endoscopy Endoscopy is an examination of internal structures using a flexible viewing tube (endoscope). In addition to examinations, doctors can use endoscopy to do biopsies and give treatment. Endoscopes... read more (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 Computed Tomography and Magnetic Resonance Imaging of the Digestive Tract Computed tomography (CT) and magnetic resonance imaging (MRI) scans are good tests for assessing the size and location of abdominal organs. Additionally, cancerous (malignant) or noncancerous... read more (CT) scan of the chest, abdomen, and pelvis and endoscopic ultrasonography Ultrasound Scanning (Ultrasonography) of the Abdomen Ultrasound scanning uses sound waves to produce pictures of internal organs (see also Ultrasonography). An ultrasound scan can show the size and shape of many organs, such as the liver and pancreas... read more (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
Doctors surgically remove GISTs.
If the cancer has spread or cannot be treated surgically, doctors often treat it with the chemotherapy drug 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 drugs 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.
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