What’s a GIST?

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sylvester cancer logoGastrointestinal stromal tumor (GIST), a soft-tissue sarcoma, is such a rare cancer that few community doctors have any experience diagnosing or managing patients with it. Large cancer centers with top sarcoma programs tend to have more experience with GIST patients.

“Even though only about 3,000 to 6,000 patients are diagnosed with GIST annually in the U.S., we see more GIST patients than any other cancer center in the southeast United States,” says Dr. Jonathan Trent, the director of the sarcoma medical research program at Sylvester Comprehensive Cancer Center. “Our experience has led us to develop innovative treatment strategies including over eight novel clinical trials specifically for GIST patients.”

A rare cancer that is difficult to diagnose.

Patients in the stages of early tumor growth rarely have symptoms. Those that do appear are indistinct and are often mistaken for other conditions, such as irritable bowel or indigestion. This can make diagnosis a slow and difficult process.

About 60% of GISTs are found in a person’s stomach, 30% in the small intestine, and the rest in the colon, rectum, or esophagus. Most people who are diagnosed are over the age of 50 but it may occur, rarely, in children.

GIST symptoms, when they do occur, may include:

  • mild abdominal pain
  • early feeling of fullness when eating
  • vomiting
  • blood in stool or vomit
  • fatigue due to low blood counts

Research-backed care can make all the difference.

If the GIST has not spread and is in an easy-to-reach place, the tumor and some of the tissue around it may be removed surgically. For small tumors, surgery may be done robotically. However, for larger tumors, open surgery is required so that surgeons can see the entire tumor.

No matter the size of the tumor, there are many factors that go into a successful outcome – and you need experienced surgical oncologists who are the best equipped remove the entire tumor.

Tyrosine kinase inhibitors (TKIs) are targeted oral therapy drugs that block signals needed for tumors to grow. TKIs may be used to treat GISTs that cannot be removed by surgery or to shrink GISTs so they become small enough to be removed by surgery. They are commonly used post-operatively to prevent recurrence. The type of TKI depends on tumor mutational status, risk factors and the stage of disease progression. There are currently three FDA-approved oral TKIs for the treatment of GIST:  imatinib (Gleevec), sunitinib (Sutent), and regorafenib (Stivarga).

what's a GISTPatients with high-risk tumors may be advised to take their TKI for three years after surgery.  It can eliminate GIST tumor cells, but in some patients, it may only kill some cells, but merely keep others from growing. This is why patients are advised by their physician to take imatinib or another TKI for life.

“We are working hard to understand the mechanisms of action and resistance of imatinib in GIST, all the time looking for even better treatment options,” says Dr. Trent. “We have on-going clinical trials for our GIST patients and collaborate with disciplines such as the genomics facility, surgical oncology, pathology, radiology, and interventional radiology to move effective treatment forward.

“Additionally, our laboratory at Sylvester is working hard to find more effective combinations of therapies to add to TKIs to improve outcomes.”

There are additional treatments that your provider may recommend, depending on your specific diagnosis.

Immunotherapy: GISTs contain tumor-infiltrating immune cells and their presence provides an opportunity and rationale for developing effective forms of immunotherapy. The treatment of GIST with immunotherapy is complex and evolving and mostly in clinical trials.

Radiofrequency Ablation (RFA): This minimally invasive treatment can destroy tumors, including liver metastases of GIST. A needle electrode is inserted into the tumor to heat and kill the tumor cells with radiofrequency energy.

Embolization: This procedure that injects substances to try to block or reduce the blood flow to cancer cells in the liver. Because the liver has two blood supplies, blocking the branch of the hepatic artery feeding the tumor helps kill off the cancer cells, but it leaves most of the healthy liver cells unharmed.

Nanoknife: This system uses electrical pulses or currents between sets of needles to puncture permanent nanometer-sized holes into the tumor. This process, called irreversible electroporation (IRE), causes the cancer cells to be unbalanced and triggers a cell “suicide,” thereby destroying the tumor. The electrical pulses are contained between the electrodes to protect surrounding healthy tissue. After the tumor is destroyed, the body naturally rids itself of the dead cells, which are replaced with healthy cells.

 


Mary Jo Blackwood, RN, MPH, is a contributing writer for UMiami Health News.
She is a two-time breast cancer thriver and freelance medical writer based in St. Louis, MO and Hartsel, CO. She has written physician-to-physician magazine articles, consumer health articles, and web pages for cancer patients, among other things.