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Frequently Asked Questions

What is GIST?
What is GIST Support International?
What is sarcoma?
What are key statistics about GIST?
What about risk factors and prevention for GIST?
How is GIST treated?
I have just been diagnosed: what do I do now?
What is my prognosis?
Should I have DNA mutational analysis of my GIST tissue?
Do I need to consult with medical experts specializing in GIST?
Are current treatments curative?

1) What is GIST?

Gastrointestinal stromal tumor (GIST) is a cancerous tumor that develops in the abdomen either along the gastrointestinal tract or close to it. GIST is a sarcoma, an uncommon type of cancer that occurs in connective and supporting tissue. The incidence of GIST is about 15 new cases per million people per year, or about 5,000 new cases per year in the USA. GIST has no known causes related to environmental factors or behavioral habits. GIST results from gene mutations that are thought to be random (except for a very few familial cases).

GIST develops in the muscle wall of the digestive tract from special “pacemaker” cells that help move food along the digestive system. Initially small tumors are contained within the muscle wall. As they grow GISTs usually grow outward from the muscle wall, not inward into the organs of the gastrointestinal tract. The most common location for GISTs is the stomach, followed by the small intestine, with a few percent occurring in the esophagus, colon, and rectum. Rarely GIST develops in other abdominal sites (including gallbladder, liver, mesentery, omentum, pelvic organs).

When GIST metastasizes (spreads) it most often affects the liver and the abdominal membranes (peritoneum, mesentery). Because many GISTs produce few symptoms, the cancer has often spread before being discovered.

GIST is diagnosed after a pathologist tests cells from the tumor. The pathologist tests for a cell-surface receptor called KIT, also called CD-117. The vast majority of GISTs test positive for KIT, but a few do not. Other pathology tests can identify GISTs that are not KIT-expression-positive (see Diagnosis and Pathology page). Differences among GISTs in the specific gene mutations they show are important in predicting their response to targeted molecular drug treatments. The pathologist can do special mutation testing to identify these characteristics.

Some GISTs (especially small ones) are cured by surgical removal. However, there is a chance of recurrence or metastasis even for small GISTs that have been completely removed. Unlike most cancers, GIST is not described by staging categories. Instead, GIST is described according to the risk of aggressive behavior (see Prognosis page). Although small GISTs with little evidence of cell division have a low risk of recurrence, no GISTs can be called truly benign.

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2) What is GIST Support International?

GSI is an online internet group of over 1070 GIST patients, caregivers, and interested friends and professionals from around the world. Anyone with an interest can join GSI; there are no membership criteria and the new subscriber does not need to provide any personal or medical data.

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3) What is sarcoma?

The name derives from the Greek “sarkoma” (fleshy growth). These cancers develop from connective tissues that act as supportive frameworks for the organs and structures of the body, such as muscles, tendons, cartilage, fibrous tissue, fat, blood vessels, nerves, and others. Connective tissues and their sarcoma counterparts are sometimes referred to as "mesenchymal" tissue, as they are derived from the mesoderm layer in embryonic development. For more about types of sarcoma, see the sites of the Sarcoma Foundation of America and Liddy Shriver Sarcoma Initiative.

The vast majority of cancers are not sarcomas but carcinomas, which develop from skin-like tissues called epithelial tissues. This includes not only the skin covering the outside of our bodies, but also the skin-like linings of our body cavities and our digestive tracts. Ordinary “stomach cancer” and “colorectal cancer” are carcinomas. Gastrointestinal stromal tumors (GISTs) should not be confused with these common cancers of the GI tract. Distinguishing GISTs from these diseases is important because GISTs behave differently and require particular drugs for treatment.

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4) What are key statistics about GIST?

Several recent scientific studies of GIST have found that the incidence is about 15 cases per million people per year. Most GISTs (and most cancers in general) occur in people older than age 50. GIST in children and young adults is quite rare.

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5) What about risk factors and prevention for GIST?

There are no known risk factors for GIST and no preventive strategies. The only exception is for GIST that runs in families (familial GIST), but this is extremely rare, with only about a dozen families reported in the medical literature.

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6) How is GIST treated?

The first option is surgery to remove the tumor(s). Surgery sometimes cures GIST, especially if the tumor is small and has not spread before being discovered. If the tumor is inoperable, or if GIST returns to the same location (recurs) or spreads to additional locations (metastasizes) after surgery, then drug treatments are available. The two drugs currently approved for inoperable or metastatic GIST are imatinib (Gleevec®) and sunitinib (Sutent®). Imatinib is the drug used first. Sunitinib is approved (in the USA) for GIST patients who are resistant to or intolerant of imatinib. See our Treatments section for details.

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7) I have just been diagnosed: what do I do now?

The answer to this question depends on whether your tumor was diagnosed as GIST before surgery (through a biopsy) or after surgery (through pathology examination of the removed tumor). Please refer to a discussion for newly diagnosed patients in the For New Patients section of our website.

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8) What is my prognosis?

The risk of recurrence or metastasis for a surgically resected GIST depends on its size and the mitotic count (a measure of how fast the tumor cells are reproducing). Please see the Prognosis section under About GIST in our website. In general, the smaller the tumor’s size at removal and the slower its rate of growth, the better the chance that it will not recur. However, even small GISTs have been known to recur, and no GIST can be categorized as definitely benign.

Patients should view any GIST diagnosis as carrying some risk for recurrence of the disease either locally or the seeding of GIST tumors to distant locations in the body to appear at some point in the future (cancerous, malignant behavior). While certain individuals might be cured by surgical resection of their GISTs, there are no conclusive criteria to guarantee that a GIST tumor is truly benign. Instead, GISTs are best categorized into low, intermediate, or high-risk tumors. Factors correlating to a better prognosis include small tumor size, gastric location, and low mitotic index (the rate of cell division). All patients, even those diagnosed with "low risk" GISTs, should have routine medical follow up for several years to monitor for reappearance of the disease. In recent years, revolutionary advancements in chemotherapy for GISTs have greatly improved the prognosis for patients with advanced or inoperable disease. Inoperable GISTs have become a manageable condition since the advent of molecular targeted drugs, such as imatinib (Gleevec®, Glivec®) and sunitinib (Sutent®). Patients and caregivers should keep in mind that the statistics from scientific articles written before 2001 will not reflect the successes achieved by
newer therapies for the treatment of GISTs.

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9) Should I have DNA mutational analysis of my GIST tissue?

Researchers are discovering new information about how the response of GIST patients to drug treatments is related to the particular mutations shown by their tumors. If you are able to have this testing done, it is a good idea. At the very least, try to ensure that adequate pathology samples are kept of your tumor to allow such testing to be done in the future, should you need it.  For labs that do this testing see Mutation Testing.

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10) Do I need to consult with medical experts specializing in GIST?

In general, this is a good idea because community oncologists and surgeons are not likely to have extensive experience with a sarcoma as rare as GIST. For a discussion of this issue see Finding Good Care.  For questions you should ask your doctor see  What To Ask Your Doctor. For a list of facilities and physicians with GIST experience, see GIST Clinics and Doctors. Other physicians seen by our members are shown on our wiki page Doctors and Clinics for GIST.

Because GISTs are uncommon, many community level physicians lack clinical experience managing GIST patients, or may be unaware of experimental therapies in clinical trial for GIST. Individuals diagnosed with GIST should consider a medical consultation at a research cancer center with a sarcoma department or recognized expertise in clinical management of GIST patients. A small percentage of GISTs lack the standard cellular traits from which a routine GIST diagnosis usually determined, but nonetheless are true although atypical GISTs. Since accurate diagnosis is essential for selecting the course of treatment, some patients may need a second opinion from a pathologist who specializes in sarcoma in order to confirm or rule out a GIST diagnosis in atypical cases.

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11) Are current treatments curative?

Surgery has the potential to be curative, especially for tumors of low or intermediate risk. Clinical trials are underway now to determine if molecularly targeted drug therapy (imatinib) can reduce the probability of recurrence if given for a period (such as 1 to 3 years) after successful surgery; the results will not be known for a few more years. For inoperable or metastatic GIST, the molecularly targeted therapies (imatinib and sunitinib) are not curative, but they do enable GIST patients to lead normal lives for years. Many patients have developed resistance to these drugs after about 2 years, but others continue to enjoy a good response for 5 years or more (as long as the drugs have been available).



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