ON THIS PAGE: You will find some basic information about this disease and the parts of the body it may affect. This is the first page of Cancer.Net’s Guide to Gastrointestinal Stromal Tumors. To see other pages, use the menu on the side of your screen. Think of that menu as a roadmap to this full guide.
The gastrointestinal (GI or digestive) tract includes the esophagus, stomach, gallbladder, liver, small intestine, colon, rectum, anus, and lining of the gut. The GI tract plays a central role in digesting food and liquid and in processing waste.
When food is swallowed, it is pushed down a muscular tube called the esophagus and enters the stomach. The muscles in the stomach mix the food and release gastric juices that help break down and digest the food. The food then moves into the small intestine, or small bowel, for further digestion before entering the large intestine. The large intestine helps remove waste from the body. The colon makes up the first five to six feet of the large intestine, and the rectum makes up the last six inches, ending at the anus.
About gastrointestinal stromal tumors (GISTs)
A tumor begins when normal cells change and grow uncontrollably. A tumor can be cancerous or benign. A cancerous tumor is malignant, meaning it can invade other tissues and spread to other parts of the body. A benign tumor means the tumor will not spread. A tumor can start in any part of the GI tract, and there are several different types of GI tumors, including gastrointestinal stromal tumors (GISTs).
GISTs are different from other more common types of GI tumors because of the type of tissue in which they start. GISTs belong to a group of cancers called soft tissue sarcoma . Soft tissue sarcomas 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.
Originally, GISTs were thought to be either muscle or nerve tumors, but modern research has shown that GISTs begin in “pacemaker” 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 digestive system.
It is important to note that all GISTs can be cancerous. Sometimes it may be difficult for the doctor to tell immediately whether a GIST is likely to come back after being surgically removed. 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, its genetic makeup, and the tumor’s location. More information about these factors and GIST treatment options are outlined in other sections of this guide.
Looking for More of an Overview?
If you would like additional introductory information, view this short video  led by an ASCO expert in sarcoma that provides basic information and areas of research. Please note this link will take you to another section on Cancer.Net.
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