Gastrointestinal Stromal Tumor (GIST)
What is a GIST?
GIST is a rare cancer of the GI tract. A tumor can happen anywhere in your GI tract, from the esophagus to the anus. GIST starts in cells called the interstitial cells of Cajal. These cells are part of the nervous system. They send signals to the muscles of your GI tract. This helps your GI tract move food and liquid through it.
What causes GIST?
Researchers are still learning what causes GIST. In most cases, an abnormal gene causes an enzyme called KIT to tell cells in the gut to keep multiplying. This causes a tumor to grow. In rare cases, a different protein causes cells to grow too much and causes a tumor. GIST may run in families who have neurofibromatosis type 1. This is a genetic condition that causes tumors to grow in parts of the nervous system.
Symptoms of GIST
You may not have any symptoms if you have early stage GIST. In later stages, symptoms may include:
Discomfort or pain in the stomach
Blood in stools or vomit
Tiredness from low levels of red blood cells (anemia)
Feeling full after eating only a small amount
Loss of appetite
Your healthcare provider will ask about your medical history and your symptoms. He or she will give you a physical exam. You may have imaging tests, such as:
Endoscopy. A flexible tube is sent down your throat. The tube has a small light and video camera. This lets your healthcare provider look at the lining of your esophagus, stomach, and upper small intestine.
X-ray. This test uses a small amount of radiation to create pictures of the inside of your body.
CT scan. This is a test that uses a series of X-rays and a computer to create images of the inside of the body.
MRI. This test uses large magnets and a computer to create images of the body.
Biopsy. Small pieces of tissue are taken from the tumor. They are looked at with a microscope in a lab. A biopsy may be done during endoscopy. Or it may be done with a thin needle. Or the tissue may be cut out with a small knife during surgery. The sample will be checked for the KIT enzyme or another protein that causes GI cells to grow too much.
Treatment for GIST
GIST can be treated in several ways. GIST grows differently in each person. The type of treatment that is best for you depends on where the tumor is, how big it is, and whether cells from the tumor have spread. This is called metastasis. Cancer cells can sometimes spread to other parts of the body. The most common places for GIST cells to spread are the liver and the lining of the stomach (peritoneal cavity).
Treatment may start with surgery. This is done to remove the tumor.
You may also have targeted therapy. Targeted therapy is the use of medicine that targets the parts of cancer cells that make them unlike normal cells. The medicines include:
Imatinib. This is mostly used for advanced-stage GIST. It may also help with earlier-stage tumors. It can be given before surgery to try to shrink the tumor, or after surgery to help lower the chance of the cancer coming back. It may not cure advanced GIST, but it can help people live longer and feel better. The medicine is taken by mouth as a pill. Side effects of imatinib are mostly mild to moderate. The most common side effect is mild nausea. Other side effects, usually mild as well, include diarrhea, fluid retention and swelling (often around the eyes), indigestion, muscle cramps, bleeding from the GIST tumor, fatigue, and a skin rash.
Sunitinib. This medicine is often used when imatinib doesn't work or if the side effects of imatinib are a problem. Sunitinib can often cause tumors to shrink or stop them from growing for a time. It may help people with GIST live longer. It is taken by mouth as a pill. The most common side effects are diarrhea, mouth irritation, and changes in skin and hair color. More serious side effects can include high blood pressure, increased risk of bleeding, and swelling.
Regorafenib. This drug is often used if other medicines are no longer working. It can often shrink tumors or slow their growth for a time. It is taken by mouth as a pill. Side effects can include diarrhea, feeling tired, high blood pressure, mouth sores, hair loss, loss of appetite, and problems with redness and pain in the palms of the hands and soles of the feet
Other treatments, such as radiation therapy, are used less often. Your healthcare provider will talk with you about the treatment that can work best for you.
When to call the healthcare provider
Call your healthcare provider if you have side effects from treatment that cause problems with your daily life.
March 21, 2017
Alteri, Rick, MD,Image reviewed by StayWell medical illustration team.,Levin, Mark, MD