Gastrointestinal Stromal Tumor - GIST

The gastrointestinal (GI or digestive) tract includes the:

  • Esophagus

  • Stomach

  • Gallbladder and bile ducts

  • Liver

  • Pancreas

  • Small intestine

  • Colon

  • Rectum

  • Anus

  • Lining of the gut

The GI tract plays a central role in digesting food and liquid and in processing waste. When you swallow food, 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 5 to 6 feet of the large intestine. The rectum makes up the last 6 inches, ending at the anus.

About gastrointestinal stromal tumor (GIST)

A tumor begins when healthy cells change and grow uncontrollably, forming a mass called a tumor. A tumor can be cancerous or benign. A cancerous tumor is malignant, meaning it can grow and spread to other parts of the body. A benign tumor means the tumor can grow but will not spread. A tumor can start in any part of the GI tract. There are several different types of GI tumors, including gastrointestinal stromal tumor (GIST).

GISTs are different from 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 sarcomas. Soft-tissue sarcomas develop in the tissues that support and connect the body. The sarcoma cells resemble the cells that hold the body together, including fat cells, muscles, nerves, tendons, joints, blood vessels, and lymph vessels.

Doctors used to think that GISTs were muscle or nerve tumors. However, research shows that GIST begins in “pacemaker” cells (or their relatives) found in the walls of the GI tract. Called interstitial cells of Cajal (ICC), they send signals to the GI tract to help move food and liquid through the digestive system.

It is important to note that GIST can be cancerous. It may be hard for the doctor to tell 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 tumor’s:

  • Size

  • Number of dividing cells

  • Genetic makeup

  • Primary location

  • Whether it has already spread

  • Whether the tumor ruptured, either on its own or as a result of surgery

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, watch this short video led by an ASCO expert in sarcoma. The video provides basic information and areas of research. Please note this link will take you to another section on Cancer.Net.