Definition

Gastrointestinal stromal tumors (GISTs) are a type of tumor found in the digestive system. This includes the esophagus, liver, stomach, gallbladder, large and small intestines, rectum, and anus. The digestive organs break down food. The body uses the nutrients and gets rid of the waste. About half of GISTs happen in the stomach. But, they can they can happen anywhere in this system.

GISTs are rare. They are considered as potentially cancerous.

Digestive System GIST may occur anywhere in the digestive system. Copyright © Nucleus Medical Media, Inc.

Causes

The cause of GISTs is not well understood.

Many people with GIST have a defect in a certain gene. In people with GIST, the gene is active when it should not be. This allows the cells to grow and divide without order. This may explain why a GIST forms.

Risk Factors

GIST is most common in people over 50 years old. Your chances may also be higher if you have:

• Inherited conditions such as neurofibromatosis type 1
• A family history of GIST—rare

Symptoms

GISTs may not cause any symptoms until they grow to a certain size. If you have them, GISTs may cause:

• Tiredness and weakness
• Fever or sweating at night
• Weight loss
• Feeling full after eating a small amount of food
• Belly pain
• Painless lump in the belly
• Nausea or vomiting
• Blood in stool or vomit
• Problems swallowing

Diagnosis

Your doctor will ask about your symptoms and health history. Your answers and a physical exam may point to a GIST.

You may have:

• Abdominal CT scan
• MRI scan
• Fine-needle biopsy —a tissue sample is taken and checked in a lab
• Tests on your genes
• PET scan

The exam and your test results will help find out the stage of the tumors. Staging guides your treatment. GISTs are staged from 1-4. Stage 1 is very localized. Stage 4 is a spread to other parts of the body.

Treatment

Treatment will depend on the stage. More than one method may be used:

• Surgery—Used to treat a GIST that has not spread. The chances of cancer spreading are higher if the GIST sac is opened during surgery. Some or all of the tumor may be removed. This depends on the size and if it's growing. Doing so lowers the chance of it growing enough to block how the digestive system works.
• Medicines—Used to shrink the tumor or stop it from growing. They may be given before surgery.

Prevention

There is no way to prevent GISTs since the cause is unknown.