Gastrointestinal Stromal Tumor (GIST)

Dr. Michael Heinrich talking with a patient in an examination room
Dr. Michael Heinrich is an international expert on GISTs, an unusual type of cancer that occurs in the gastrointestinal (digestive) tract.

Gastrointestinal stromal tumors (GISTs) are relatively rare tumors found in the gastrointestinal (digestive) tract. The GIST cancer team at the OHSU Knight Cancer Institute has years of experience caring for patients with this type of cancer.

We offer you:

  • GIST specialists, led by internationally renowned medical oncologist Michael Heinrich, M.D.
  • A team that treats more patients with GISTs than any other Oregon hospital.
  • Team-based care with fellowship-trained surgeons, gastroenterologists and other specialists working together. 
  • Gleevec, a targeted medication developed through pioneering work at OHSU.
  • A deep commitment to research, including clinical trials and a center devoted to early detection.
  • Care at a hospital ranked among the best in the nation by U.S. News & World Report.
  • A full range of support services for you and your family.
     

Understanding gastrointestinal stromal tumors

What are GISTs?

Gastrointestinal stromal tumors start in the wall of the GI tract. They may start in what are called the interstitial cells of Cajal, or ICCs. These cells are sometimes called the pacemakers of the GI tract because they signal muscles to move food and liquid through. More common GI cancers, such as colon cancer, start in different cell types.

GISTs can start anywhere in or near the GI tract. About 60% start in the stomach and about 30% in the small intestine. The rest develop in the esophagus, large intestine or, very rarely, other parts. Most but not all GISTs are cancer.

Medical illustration of lower gastrointestinal anatomy
GISTs can start anywhere in or near the gastrointestinal (GI) tract but are most common in the stomach and small intestine.

Who gets GISTs?

About 4,000 to 6,000 people are diagnosed with GISTs in the U.S. each year. GISTs make up less than 1% of GI cancers.

Survival rates

The American Cancer Society reports that 83% of people diagnosed with a GIST from 2008 to 2014 survived at least five years. That number rose to 94% if the cancer hadn’t spread beyond the organ where it started. 

It's important to remember that five-year survival rates are averages; they can't predict the outcome for any one patient. They are also based, by definition, on treatments that were available five or more years ago.

Risk factors

Doctors don’t fully understand what causes GISTs, but they have identified risk factors that include:

  • Age: Most people are older than 50, though these tumors can occur at any age.
  • Gender: Men are at slightly higher risk.
  • Race: African Americans are more likely to develop GISTs.
  • Inherited conditions: Most cases are not inherited. However, a rare inherited condition called primary familial GIST syndrome, caused by a genetic mutation, puts family members at higher risk. OHSU offers expert genetic testing and risk assessment to help you identify and manage risk.

Symptoms

Symptoms of gastrointestinal stromal tumors include:

  • Blood in stool or vomit
  • Abdominal pain, possibly severe
  • Swollen abdomen or lump in abdomen
  • Fatigue
  • Painful swallowing
  • Loss of appetite, or feeling full after eating very little
  • Weight loss 

Diagnosis

Your care team will ask you about your symptoms and medical history. We will also conduct a thorough physical exam to check for lumps or signs of tenderness or swelling. We may recommend other tests, such as: 

Imaging tests: These noninvasive tests provide detailed images of your digestive tract. Common tests we may use include:

  • CT (computed tomography) scan
  • MRI (magnetic resonance imaging) scan
  • PET (positron emission tomography) scan 

Endoscopic ultrasound: We guide an endoscope (a long, thin tube with a light and camera) down your throat. This enables us to see your esophagus, stomach and the first part of your small intestine. An ultrasound probe at the tip creates images. Our interventional endoscopists (gastroenterologists with special training) do hundreds of these a year. Patients are kept comfortable, usually with deep sedation under an anesthesiologist’s supervision.

Biopsy: We remove a small tissue sample, typically with a thin needle during an endoscopic ultrasound. The ultrasound helps guide the needle, ensuring precision. A type of doctor called a pathologist uses a microscope to check the tissue for cancer cells.

Staging

Staging plays an important role in treatment decisions. Your care team will determine the stage of your cancer based on:

  • Tumor size
  • Whether the cancer has spread to lymph nodes or distant parts of your body
  • How fast cancer cells are growing and dividing (a measure called mitotic rate) 

This is the staging for the most common GIST, one that starts in the stomach or, rarely, in a layer of fatty abdominal tissue called the omentum. Read more on the American Cancer Society website.

Tumor sizes

Medical Illustration of Tumor Sizes, full size

Stage I: The tumor has not spread to nearby lymph nodes, and mitotic rate is low.

  • Stage IA: The tumor is no larger than 5 centimeters.
  • Stage IB: The tumor is larger than 5 centimeters but not larger than 10 centimeters.

Stage II: The cancer has not spread to nearby lymph nodes. In addition, the tumor is no larger than 5 centimeters and the mitotic rate is high; or the tumor is larger than 10 centimeters and the mitotic rate is low.

Stage III: The cancer has not spread to nearby lymph nodes, and the mitotic rate is high.

  • Stage IIIA: The tumor is larger than 5 centimeters but not larger than 10 centimeters. 
  • Stage IIIB: The tumor is larger than 10 centimeters.

Stage IV: The cancer has spread to nearby lymph nodes and/or to distant parts of the body.
 

Dr. Heinrich examining a GIST patient
Dr. Heinrich examines a GIST patient who took part in a clinical trial.

Treatments

Your care team will work with you to recommend a treatment plan for your specific needs and wishes.

Targeted therapy

Targeted therapy treats the cancer using medication. You may be a candidate for Gleevec, a daily pill developed through groundbreaking work by OHSU Knight Cancer Institute Director Brian Druker, M.D. 

Gleevec works to shrink tumors by blocking proteins GISTs need to grow. In about two out of three patients, the tumors shrink by 50% or more. Your care team may recommend Gleevec before surgery to shrink the tumor or after to help keep cancer from spreading or returning.

Sometimes, tumors become resistant to Gleevec over time. In this case, you might receive a second medication, sunitinib (Sutent). Other medications may be available through clinical trials.

Surgery

Our surgeons have exceptional expertise in treating gastrointestinal cancers, including GISTs. They trained at top U.S. cancer centers, including Johns Hopkins and the National Cancer Institute.

  • Small tumor: If the tumor hasn’t spread, the cancer can often be entirely removed. A minimally invasive laparoscopic surgery with small incisions may be an option. Lymph nodes are rarely removed because, unlike in many other cancers, GISTs usually don’t spread to them.
  • Large tumor: If the tumor is large or invading other organs, we may need to take out parts of these as well to remove as much of the cancer as possible.
     

Learn more

For patients

Call 503-494-7999 to:

  • Request an appointment
  • Seek a second opinion
  • Ask questions

Locations

Parking is free for patients and their visitors.

Center for Health & Healing Building 2
3485 S.W. Bond Ave.
Portland, OR 97239

Map and directions

Refer a patient

Tumors vanish

Candid photo of Pete Julian at a ball park

Meet Pete Julian, who saw his GISTs disappear after starting on Gleevec, a targeted medication developed through pioneering work at OHSU.

Results show promise

Dr. Michael Heinrich headshot photo

Learn about promising findings of Dr. Michael Heinrich’s work to test a GIST medication in clinical trials.

Read more

Learn more about OHSU Knight Cancer Institute treatments:

Stay informed

Blog: Learn about the latest findings on our Cancer Translated blog.

News: Read about research breakthroughs, patient care and many other topics on our OHSU News site.