Gastrointestinal Stromal Tumor (GIST)


Gastrointestinal Stromal Tumors (GISTs), are a rare type of cancer that can form in the gastrointestinal (GI) tract.

GISTs are different from other common GI cancers in that they start in a specific type of cell called interstitial cells of Cajal (ICC). Sometimes known as “pacemaker” cells, ICCs are part of the nervous system, and control the automatic, rhythmic contraction of muscles that move food and liquids through the GI tract. When these specialized cells grow out of control, this can result in a gastrointestinal stromal tumor.

GISTs can form anywhere in the digestive tract, from the anus to the esophagus. However, they most often start in the stomach or small intestine. More than half of GISTs begin in the stomach, while around 30% begin in the small intestine

GISTs are very uncommon, with only about 5,000-6,000 cases diagnosed in the U.S. each year.

Why Hoag for Gastrointestinal Stromal Tumor Evaluation and Treatment? 

Many physicians may have never even heard of GISTs, much less diagnosed and treated a case. As the OC’s top choice for world-class, comprehensive cancer care with cancer survival rates that continuously exceed national averages, the Hoag Family Cancer Institute has seen, diagnosed and successfully treated more GIST cases than any other center in our area.

That’s a deep well of experience that can be put to work for you. Couple that with Orange County’s most advanced techniques, technology and treatment options, and Hoag is your best choice for a fuller and more complete recovery after a GIST diagnosis.

A commitment to the latest and most advanced treatment options. Fully-integrated and condition-specific teams, working together toward your recovery. The latest and most advanced treatment options, from a designated Center of Excellence in Robotic Surgery (COERS) that does more robotic-assisted procedures than any treatment center in California. That’s GI cancer care at Hoag, and your path to making a GIST diagnosis the moment you started to heal.

Meet Hoag Family Cancer Institute’s specialized cancer teams

Symptoms & Causes of Gastrointestinal Stromal Tumors

GISTs often cause no noticeable symptoms, making early detection harder. Many gastrointestinal stromal tumors are discovered accidentally during surgery or imaging of the abdomen for other conditions.

As the tumor grows larger or spreads, however, GISTs may begin to cause noticeable symptoms. These may include:

  • Early satiety, which is feeling full after only eating a small amount of food.
  • Abdominal pain or discomfort
  • A lump or mass in the abdomen
  • Nausea or vomiting.
  • Fatigue or weakness due to anemia caused by low red blood cell count
  • Seeing blood in the stool or vomit
  • Loss of appetite
  • Bowel obstruction
  • Difficulty swallowing
  • Losing weight without trying
Causes and Risk Factors For GISTs

Most GISTs are due to a defective gene that causes the body to produce too much of an enzyme called KIT (AKA tyrosine kinase). KIT is responsible for telling interstitial cells of Cajal (ICC) when to grow and when to die.

When too much KIT is produced, ICCs may begin to stay alive longer than they should and reproduce out of control, causing GISTs to form. GISTs can also sometimes be caused by the overproduction of a protein called PDGFRA.

There are a few known factors that may increase your risk of developing GISTs. These include:

  • Your age, as most cases of GISTs occur in those older than 50
  • Being male
  • Having Familial GIST Syndrome, which is a rare mutation of the KIT genes that can be passed down through families. Those with familial GIST syndrome may develop GIST at younger ages, or in multiple places in the digestive tract
  • Having Neurofibromatosis type 1 (AKA von Recklinghausen disease) which is a rare disorder that can cause tumors to form all over the body
  • Having Carney-Stratakis syndrome, which is another rare genetic disorder that can cause GISTs

Diagnosis & Tests for Gastrointestinal Stromal Tumors

Because GISTs often cause no noticeable symptoms, they are usually discovered accidentally during medical examinations and imaging for other conditions of the GI tract or abdomen.

If a doctor suspects you may have GISTs, he or she will likely ask you about your medical history and symptoms, if any, followed by a thorough physical examination, including feeling for lumps or masses in the abdomen that can be felt through the skin.

Depending on the outcome of these examinations, you may be asked to complete other tests to confirm or rule out a diagnosis of GIST. These may include:

  • Imaging Tests, which may include computed tomography (CT) scans, magnetic resonance imaging (MRI) and/or positron emission tomography (PET) scans.
  • Endoscopic procedures, in which a specialist uses a long, flexible tube with a light and a camera on the tip to directly examine your GI tract. Explore Hoag’s Orange County endoscopy centers near you
  • Biopsy, in which a sample of tissue is removed, usually by endoscopy, so it can be examined in a lab
Orange County’s Most Advanced Diagnosis of Conditions of the Gastrointestinal Tract

As Orange County’s recognized leader in the accurate diagnosis and treatment of conditions involving the GI tract, the Hoag Digestive Health Institute is here for those facing serious conditions involving the digestive organs, including GiST, stomach cancer and colon cancer.

At Hoag, advanced procedures used to diagnose or treat conditions involving the GI tract include:

Management & Treatment of Gastrointestinal Stromal Tumors

The primary treatment option for GISTs is surgical removal of the tumor. However, in cases in which a GIST is very large, located in a difficult-to-reach place, or in which tumors have spread to other parts of the body, targeted drug therapy may be used to shrink the tumor prior to surgery.

Targeted drug therapy for GISTs often involves a medication called imatinib which attaches to and blocks KIT, the protein that, when overproduced by mutated cells, is responsible for the uncontrolled growth and spread of most GISTs. Imatinib can halt the growth of GISTs, or shrink tumors enough that surgery may become an option.

If a patient’s GIST becomes resistant to imatinib and begins to grow again, there are other targeted drugs that can be tried, including ripretinib, regorafenib and sunitinib.

Meet Hoag’s specialized cancer nurse navigators, who help patients and their families find support before, during and after treatment.

Prevention of Gastrointestinal Stromal Tumors

While the search for new GIST risk factors and treatment options continues, there’s currently no known way to definitely prevent yourself from developing GISTs. However, healthy lifestyle choices may make your body better able to repel GISTs, or make it easier to recover if you do develop a GIST. These may include:

  • Eat a balanced, healthy diet
  • Maintain a healthy weight
  • Don’t smoke
  • Use alcohol in moderation
  • Get regular exercise

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