What is GIST?
A gastrointestinal stromal tumor (GIST) is a type of tumor that occurs in the gastrointestinal (GI or digestive) tract, including the esophagus, stomach, gallbladder, liver, small intestine, colon, rectum, and lining of the gut. GISTs are different from other types of gastrointestinal tumors because of the type of tissue in which they start.
Originally, GISTs were thought to be either muscle or nerve tumors, but recent research points to GISTs starting in cells found in the walls of the GI tract, called interstitial cells of Cajal (ICC); these cells send signals to the GI tract to help move food and liquid through the system.
GISTs belong to a group of cancers called soft tissue sarcoma. Soft tissue sarcomas are a group of cancers that develop in the tissues that support and connect the body, and the sarcoma cells resemble the cells that hold the body together, including fat cells, muscles, nerves, tendons, joints, blood vessels, or lymph vessels.
It is important to note that GISTs can be either benign or malignant. Sometimes it may be hard for the doctor to tell immediately whether a GIST is likely to come back after treatment. As a result, the doctor will look at many factors to determine the best treatment, including the size of the tumor, whether it has already spread, how many dividing cells there are, and the tumor’s location.
Because GIST cancers arise from the GI tract wall, they are usually attached to the outside of the involved organ, growing outward; this is sometimes referred to as exophytic. Occasionally a GIST may grow inward through the muscle layer of the GI tract wall and then develop partly inside the digestive tract lumen; this is sometimes called endophytic.
More than half of GISTs start in the stomach. Most of the remaining start in the small intestine, but GISTs can be found anywhere in the GI tract.
How common is GIST?
GIST is one of the not so common tumors Most primary care physicians and many pathologists and oncologists go through their entire professional careers without seeing a single GIST. This is important to patients because misdiagnosis can delay the start of appropriate treatment.