Gastrointestinal Stromal Tumors (GIST)

Gastrointestinal stromal tumors—often shortened to GIST—are rare tumors that develop in the lining of the digestive tract. They're often small and initially slow growing, so they might not cause symptoms during the earliest stage of disease. 

What Is a GIST? 

GISTs form in the lining of your gastrointestinal (digestive) tract. They originate from cells called "interstitial cells of Cajal" or "ICCs" that initiate peristalsis, or muscle contractions, that propel swallowed food materials through the GI tract. 

GISTs can form at any point from the esophagus (inside your chest) to the anus, but most commonly form in the stomach or small intestine first—60-70% of GISTs begin in the stomach and 20-30% in the small intestine. 

Fortunately, many GISTs are identified early and can be removed with surgical excision.

Types of GISTs 

GISTs can be low risk when discovered early in the stomach when they are small and low grade. But as GISTs become larger and higher grade, or if they arise from other parts of the GI tract outside of the stomach, their risk for developing metastasis increases. These high-risk GISTs are often treated with a combination of surgery and chemotherapy.

Gastrointestinal Stromal Tumor Symptoms

GISTs start small and grow slowly, so you may not have symptoms at first. However, as the cancer grows, you may experience GIST symptoms, including: 

• Digestive symptoms: Constipation, bowel obstruction, or changes in your bowel movements, such as bloody stool, nausea, or vomiting
• Pain: Abdominal pain, especially after eating (but keep in mind the vast majority of abdominal pain is not caused by an undiagnosed GIST, as GIST affects approximately 4.3 per million per year in the United States).
• Other symptoms: Fatigue, anemia, a feeling of fullness when you haven't eaten much, unexpected weight loss, and a lump you can feel when you press on your belly 

What Causes a GIST? 

Like other tumors and forms of cancer, GISTs result from mutations in the DNA of cells that cause them to grow and multiply out of control.

In GISTs, the cause of these changes is usually a mutation in one of two genes: KIT or PDGRFA. The unmutated version of these genes helps the normal cells divide and grow. In a healthy person, ICCs initiate peristalsis and grow only in a very controlled fashion. In people with a GIST, the mutated genes have been turned on when they shouldn't be, and they direct the ICCs to multiply without control. 

Other causes of GISTs include rare genetic disorders (neurofibromatosis type 1 and Carney-Stratakis syndrome) or a rare hereditary condition called familial GIST syndrome. 

While experts know the cause of most GISTs is changes to the KIT and PDGRFA genes, the reason for the gene changes isn't well understood. There are no known environmental or lifestyle risk factors, and some GISTs may simply result from random changes in the DNA of ICCs. 

GIST Treatment at Mass General Brigham Cancer Institute 

Mass General Brigham Cancer Institute features one of the largest and most experienced centers in the Unites States for the treatment of GIST. Explore our GIST Treatment Program to learn about our collaborative and caring approach to the diagnosis and treatment of patients with confirmed or suspected GIST. 

FAQs About GIST Symptoms and Causes 

When you or a loved one receives a cancer or tumor diagnosis, it's normal to wonder what it means for your life. Common questions include: 

Is GIST Serious? 

Often, GISTs don't cause many symptoms, especially at first, but you should take them seriously. Experts believe that even low-risk GISTs have the potential to become dangerous, so it's best to seek care at a GIST treatment center to decide how they can be best managed. 

What Are the Causes of GIST? 

Usually, GISTs are caused by mutations in the KIT or PDGRFA genes, but experts don't know what causes these mutations. Other possible causes of GIST include rare genetic disorders and a hereditary condition called familial GIST syndrome. 

Is a GIST Hereditary? 

It can be but in rare cases. Most GISTs are sporadic. Some GISTs are caused by a condition called familial GIST syndrome, in which an abnormal gene passed from parent to child causes GIST to form. Often, the cause for the mutated genes that result in GIST is unknown.