Gastrointestinal Stromal Tumor (GIST)

What is it?
A gastrointestinal stromal tumor, (GIST), is a type of growth that is usually benign, (non-cancerous), that is present in the stroma, a layer of  connective tissue in the wall of the stomach or the intestine. These tumors are most often found in the stomach, or the first part of the small intestine, but any part of the GI tract can be affected. Although classified as benign, it appears that some GISTs, can become malignant, invading, and spreading to other tissues. The risk of a GIST becoming malignant is related to its size and location. Larger GISTs are more likely to become malignant and GISTs on the stomach are less likely, compared to GISTs in other areas of the intestinal tract.

Who gets it?
GISTs make up only 1% of cancers starting in the GI tract. It is thought to affect 7-20 people per one million in the United States each year. It occurs most often in middle aged and older people and is rare in people under 40. No risk factors for GISTs have been identified.

What are the symptoms?
Sometimes, this condition has no symptoms, and the presence of the GIST is found incidentally on an upper endoscopy, barium study or CT scan done for other purposes. They are often associated with non-specific symptoms such as:

  • Feeling full fast when eating, even after only several bites
  • Bloating
  • Low blood sugar; very rarely this will be the presenting feature. The tumor can produce a chemical that works like insulin in your blood, allowing tissues to take up too much of the sugar in the blood so there is little left.

If the mass grows large enough it can ulcerate or cause obstruction of the bowel. If this happens, other symptoms are possible and include:

  • Visible GI bleeding
  • Abdominal mass
  • Abdominal pain

How is it diagnosed?
With or without endoscopic ultrasound

  • Upper Endoscopy
  • Barium study
  • CT scan
  • Ultrasound

How is it treated?
Treatment depends on the size and the location of the GISTs. Often if 2 cm in size or larger, they will be surgically removed. Sometimes treatment will begin with chemotherapy to shrink the tumor size or stop its growth before surgery. Other times, chemotherapy will be used alone. Chemotherapy targets the production of the signal that is leading to the rapid cell growth and cell division in the tumor.

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