Definition

Gastrointestinal stromal tumors (GISTs) are a type of tumor that occurs in the digestive system. The digestive system includes the esophagus, liver, stomach, gall bladder, large and small intestines, and rectum. The digestive system processes food to fuel the body and gets rid of waste. About half of GISTs occur in the stomach, but they can occur anywhere in the digestive system.

Theories about GISTs say that they begin in special cells of the digestive system. These cells are called interstitial cells of Cajal (ICCs). They send signals that tell the digestive system to contract, which moves food and liquid through the digestive system.

GISTs are rare. All GISTs are now considered potentially malignant (cancerous).

Digestive System

GIST may occur anywhere in the digestive system.

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Causes

The cause of GISTs is not well understood.

Many people with GIST have a mutation (defect) in a gene called c-kit. Usually, this gene is not active. However, in people with GIST, the c-kit gene often has a defect and is active, which enables the cells to grow and divide uncontrollably. This may explain why a GIST forms.

Risk Factors

Risk factors for GIST are mostly unknown. Possible risk factors include:

• Neurofibromatosis (a genetic disorder of the nervous system)
• Family history of GIST—Very rarely, GISTs have been found in members of the same family.

GIST is most common in people over age 50. It is very rare in children.

Symptoms

GISTs may not cause any symptoms until they grow to a certain size. If you have any of these symptoms, do not assume it is due to a GIST. These symptoms may be caused by other conditions. Tell your doctor if you have any of these:

• Fatigue (tiredness and weakness)
• Fever; sweating at night
• Weight loss
• Feeling full after eating a small amount of food
• Abdominal pain
• Painless lump in the abdomen
• Nausea and/or vomiting
• Blood in stool or vomit
• Problems swallowing (for tumors in the esophagus)

Diagnosis

Your doctor will ask about your symptoms and medical history. A physical exam will also be done.

Your doctor may do one or more of these tests to find the cause of your symptoms or to investigate for a tumor:

• Barium swallow —involves drinking a fluid that makes the esophagus, stomach, and intestines show up on x-ray
• Barium enema —barium is injected into the rectum so that the large intestine can be clearly seen on x-ray
• Ultrasound —a test that uses sound waves to look at the digestive system
• Endoscopy—a thin, lighted tube is inserted down the esophagus to look at the upper digestive system
• Colonoscopy —a thin, lighted tube is inserted up the rectum to look at the lower digestive system
• Endoscopic ultrasound —a thin, lighted tube with a tiny ultrasound transducer within it is passed into the esophagus
• Computed tomography (CT) scan —a type of x-ray that uses a computer to make pictures of the inside of the digestive system
• Magnetic resonance imaging (MRI) scan —a test that uses magnetic waves to make pictures of the inside of the digestive system
• Positron emission tomography (PET) scan —radioactive material is injected into a vein to measure activity in the cells of your body (Cancerous areas are usually more active, so they attract more of the radioactive material. They can then be seen on the scan.)

If one of these tests finds a mass, the doctor may do a biopsy. A fine-needle biopsy may be used to diagnose a GIST. The doctor will use a CT scan or endoscopy to guide a tiny, hollow needle into the mass. The sample will be tested to determine if the mass is cancerous. In other cases, a surgery may have to be performed to take the biopsy.

Treatment

Talk with your doctor about the best treatment plan for you. Treatment options include:

Prevention

GISTs cannot be prevented.