Gastrointestinal Stromal Tumors (GIST)

Gastrointestinal stromal tumors (GISTs) are a rare type of tumor that begins in the digestive tract, also called the gastrointestinal (GI) tract. They start most often in the stomach or small intestine, but they can form anywhere along the GI tract.
GISTs grow from special cells in the wall of the GI tract called interstitial cells of Cajal. These cells help control the movement of food through the digestive system. GISTs can be slow-growing or more aggressive, and they may grow into nearby tissue or spread to other parts of the body.

Types & Stages

GIST is the main tumor type in this group. While GISTs can look similar under a microscope, they can behave very differently from one person to another.

To help guide care, doctors describe a GIST's risk of growing or spreading using three main features:

• Tumor size. Larger tumors tend to carry a higher risk.
   
• Location. Where the tumor starts in the GI tract can affect how it is likely to behave. For example, tumors in the small intestine may behave differently from those in the stomach.
   
• Mitotic rate. This measures how quickly the tumor cells are dividing. A higher mitotic rate suggests a faster-growing tumor.

GISTs are also often described in simple terms based on how far they have spread:

• Localized. The tumor is found only where it started and has not spread.
   
• Regional spread. The tumor has grown into nearby tissues or organs.
   
• Distant spread (metastatic). The cancer has spread to distant parts of the body, such as the liver or the lining of the abdomen.

Your care team will use these features and your overall health to plan treatment.

Signs & Symptoms

GISTs often cause few or no symptoms early on, and some are found by chance during tests or procedures done for another reason.

Visit a doctor if you are experiencing any of these symptoms:

• Belly pain or discomfort
• Bleeding in the digestive tract
• Black or tarry stools
• Unexplained fatigue
• Nausea or vomiting
• Trouble eating
• Feeling full quickly when eating

Many of these symptoms can be caused by conditions that are not cancer. Still, it is important to pay attention to your body. If symptoms are new, last more than a few weeks, or are unusual for you, talk with a healthcare provider.

Diagnosis

Tests and procedures used to diagnose a GIST may include:

• Physical exam and history. Your doctor checks your overall health and asks about your symptoms and health history.
  Imaging tests. A CT scan or MRI can show the size and location of the tumor and whether it has spread to other parts of the body.
   
• Endoscopy or endoscopic ultrasound. When needed, a thin, lighted tube with a camera is passed into the GI tract to view the tumor. An endoscopic ultrasound uses sound waves to create detailed images and can help guide a tissue sample.
   
• Biopsy. A biopsy removes a small sample of the tumor so it can be examined under a microscope by a pathologist. This is the main way to confirm a GIST and learn more about it.

Treatment

Treatment for a GIST depends on the tumor's size, location, and risk features, whether it has spread, and your overall health. Your care team can help explain the benefits and risks of each option.

Treatment may include:

• Surgery. When the tumor can be safely removed, surgery is the main treatment. The goal is to remove the entire tumor, often with a margin of healthy tissue. Surgery may cure many people with localized GISTs.
   
• Targeted therapy. Targeted medicines focus on specific changes inside GIST cells. Imatinib is a common targeted medicine used for many GISTs. It may be given to shrink a tumor before surgery, lower the chance of return after surgery, or treat tumors that have spread.
   
• Other targeted medicines. If a GIST does not respond to imatinib, comes back, or spreads, other targeted medicines may be used to help control the cancer.

Clinical trials may also be an option. These studies test new treatments or new ways to use current ones. Ask your care team whether a clinical trial may be right for you.

Causes & Risk Factors

The exact cause of a GIST is not always known. Many GISTs are linked to changes in the KIT or PDGFRA genes within the tumor cells. These gene changes cause the cells to grow out of control.

Most of these changes are not inherited. They happen on their own and are found only in the tumor, not passed down in families.

In rare cases, certain inherited syndromes can increase the risk of developing GISTs. People with a strong family history of GISTs or a known inherited condition may benefit from talking with a healthcare provider or genetic counselor.

Having a risk factor does not mean you will develop a GIST, and many people with the disease have no known risk factors. Talk with your healthcare provider about your personal risk.

Screening

There is no routine screening test for gastrointestinal stromal tumors for people at average risk.

Because GISTs are rare, they are most often found when a person has symptoms or during tests done for another reason. There is no recommended test to look for GISTs in people who feel well and have no symptoms.

People with a known inherited syndrome or a strong family history of GISTs should talk with a healthcare provider, who may suggest closer monitoring in certain cases.

If you have symptoms that are new, persistent, or unusual for you, do not wait. Talk with a healthcare provider about your symptoms and whether further evaluation is needed.

This information is for general education only and is not a substitute for medical advice. Please consult a qualified healthcare provider for diagnosis, treatment recommendations, and guidance based on your personal health history.