Gastrointestinal stromal tumors are a disease in which malignant (cancer) cells form in the tissues of the wall of the stomach or intestines.

Gastrointestinal stromal tumors (GIST) usually begin in cells in the tissues of the wall of the stomach or intestines. These cells, called interstitial cells of Cajal, help food move along the digestive tract.

Childhood GIST usually occurs in the stomach. It is more common in girls, and typically appears in the teen years.

GIST in children is not the same as GIST in adults. Patients should be seen at centers that specialize in the treatment of GIST.

GIST may develop as part of a syndrome.

GIST may occur as part of the following syndromes:

• Carney triad (GIST, lung chondroma, and paraganglioma).
• Carney-Stratakis syndrome (GIST and paraganglioma).

Signs and symptoms of GIST include anemia and a lump in the abdomen.

These and other signs and symptoms may be caused by GIST or by other conditions.

Check with your child's doctor if your child has any of the following:

• Anemia (tiredness, dizziness, fast or irregular heartbeat, shortness of breath, or pale skin).
• A lump in the abdomen.
• A blockage of the intestine (cramping pain in the abdomen, nausea, vomiting, diarrhea, constipation, and swelling of the abdomen).

Tests that examine the digestive tract are used to help diagnose GIST.

The following tests and procedures may be used:

• Physical exam and health history: An exam of the body to check general signs of health, including checking for signs of disease, such as lumps or anything else that seems unusual. A history of the patient’s health habits and past illnesses and treatments will also be taken.
• Gene testing: A laboratory test in which cells or tissue are analyzed to look for changes in the KIT, PDGFA, and SDH genes. It is important to know whether there are changes in these genes in order to diagnose GIST and plan treatment.
• MRI (magnetic resonance imaging): A procedure that uses a magnet, radio waves, and a computer to make a series of detailed pictures of areas inside the body. This procedure is also called nuclear magnetic resonance imaging (NMRI).
• CT scan (CAT scan): A procedure that makes a series of detailed pictures of areas inside the body, taken from different angles. The pictures are made by a computer linked to an x-ray machine. A dye may be injected into a vein or swallowed to help the organs or tissues show up more clearly. This procedure is also called computed tomography, computerized tomography, or computerized axial tomography.
• PET scan (positron emission tomography scan): A procedure to find malignant tumor cells in the body. A small amount of radioactive glucose (sugar) is injected into a vein. The PET scanner rotates around the body and makes a picture of where glucose is being used in the body. Malignant tumor cells show up brighter in the picture because they are more active and take up more glucose than normal cells do.

• X-ray: An x-ray is a type of energy beam that can go through the body and onto film, making a picture of areas inside the body, such as the abdomen or the area where the tumor formed.
• Biopsy: The removal of cells or tissues so they can be viewed under a microscope by a pathologist to check for signs of cancer.
  • Fine-needle aspiration: The removal of tissue using a thin needle.
  • Endoscopy: A procedure to look at organs and tissues inside the body to check for abnormal areas. An endoscope is inserted through an incision (cut) in the skin or opening in the body, such as the mouth or anus. An endoscope is a thin, tube-like instrument with a light and a lens for viewing. It may also have a tool to remove tissue or lymph node samples, which are checked under a microscope for signs of disease.

  The following laboratory test may be done to study the tissue samples:

  • Immunohistochemistry: A laboratory test that uses antibodies to check for certain antigens (markers) in a sample of a patient’s tissue. The antibodies are usually linked to an enzyme or a fluorescent dye. After the antibodies bind to a specific antigen in the tissue sample, the enzyme or dye is activated, and the antigen can then be seen under a microscope. This type of test looks for the enzyme SDH in a sample of the patient's tissue. When SDH is not present, it is called SDH-deficient GIST. It is important to know whether the cancer is SDH-deficient in order to plan treatment.

After GIST has been diagnosed, tests are done to find out if cancer cells have spread to nearby areas or to other parts of the body.

The process used to find out if GIST has spread to nearby areas or other parts of the body is called staging. GIST may spread to the lymph nodes, liver, and peritoneum. There is no standard staging system for childhood GIST. The results of tests and procedures done to diagnose GIST are used to help make decisions about treatment.

Sometimes childhood GIST recurs (comes back) after treatment.

There are three ways that cancer spreads in the body.

Cancer can spread through tissue, the lymph system, and the blood:

• Tissue. The cancer spreads from where it began by growing into nearby areas.
• Lymph system. The cancer spreads from where it began by getting into the lymph system. The cancer travels through the lymph vessels to other parts of the body.
• Blood. The cancer spreads from where it began by getting into the blood. The cancer travels through the blood vessels to other parts of the body.

Cancer may spread from where it began to other parts of the body.

When cancer spreads to another part of the body, it is called metastasis. Cancer cells break away from where they began (the primary tumor) and travel through the lymph system or blood.

• Lymph system. The cancer gets into the lymph system, travels through the lymph vessels, and forms a tumor (metastatic tumor) in another part of the body.
• Blood. The cancer gets into the blood, travels through the blood vessels, and forms a tumor (metastatic tumor) in another part of the body.

The metastatic tumor is the same type of cancer as the primary tumor. For example, if GIST spreads to the liver, the cancer cells in the liver are actually GIST cells. The disease is metastatic GIST, not liver cancer.

Treatment Option Overview

There are different types of treatment for children with GIST.

Some treatments are standard (the currently used treatment), and some are being tested in clinical trials. A treatment clinical trial is a research study meant to help improve current treatments or obtain information on new treatments for patients with cancer. When clinical trials show that a new treatment is better than the standard treatment, the new treatment may become the standard treatment.

Because cancer in children is rare, taking part in a clinical trial should be considered. Some clinical trials are open only to patients who have not started treatment.

Children with GIST should have their treatment planned by a team of doctors who are experts in treating childhood cancer.

Treatment will be overseen by a pediatric oncologist, a doctor who specializes in treating children with cancer. The pediatric oncologist works with other pediatric health professionals who are experts in treating children with cancer and who specialize in certain areas of medicine. This may include the following specialists and others:

• Pediatrician.
• Pediatric surgeon.
• Pathologist.
• Pediatric nurse specialist.
• Social worker.
• Rehabilitation specialist.
• Psychologist.
• Child-life specialist.

Two types of standard treatment are used:

Surgery

Surgery to remove the cancer is a treatment for SDH-deficient GIST.

Targeted therapy

Targeted therapy is a type of treatment that uses drugs or other substances to attack cancer cells. Targeted therapies usually cause less harm to normal cells than chemotherapy or radiation therapy do.

• Tyrosine kinase inhibitor therapy: These drugs block signals needed for tumors to grow. Imatinib and sunitinib are used to treat SDH-deficient GIST and GIST with changes in the KIT or PDGFR gene.

Chemotherapy

Chemotherapy is a cancer treatment that uses drugs to stop the growth of cancer cells, either by killing the cells or by stopping them from dividing. When chemotherapy is taken by mouth or injected into a vein or muscle, the drugs enter the bloodstream and can reach cancer cells throughout the body (systemic chemotherapy).

Treatment for childhood GIST may cause side effects.

Side effects from cancer treatment that begin after treatment and continue for months or years are called late effects. Late effects of cancer treatment may include:

• Physical problems.
• Changes in mood, feelings, thinking, learning, or memory.
• Second cancers (new types of cancer) or other conditions.

Some late effects may be treated or controlled. It is important to talk with your child's doctors about the possible late effects caused by some treatments. 

Patients may want to think about taking part in a clinical trial.

For some patients, taking part in a clinical trial may be the best treatment choice. Clinical trials are part of the cancer research process. Clinical trials are done to find out if new cancer treatments are safe and effective or better than the standard treatment.

Many of today's standard treatments for cancer are based on earlier clinical trials. Patients who take part in a clinical trial may receive the standard treatment or be among the first to receive a new treatment.

Patients who take part in clinical trials also help improve the way cancer will be treated in the future. Even when clinical trials do not lead to effective new treatments, they often answer important questions and help move research forward.

Patients can enter clinical trials before, during, or after starting their cancer treatment.

Some clinical trials only include patients who have not yet received treatment. Other trials test treatments for patients whose cancer has not gotten better. There are also clinical trials that test new ways to stop cancer from recurring (coming back) or reduce the side effects of cancer treatment.

Clinical trials are taking place in many parts of the country. Information about clinical trials supported by NCI can be found on NCI’s clinical trials search webpage. Clinical trials supported by other organizations can be found on the ClinicalTrials.gov website.

Follow-up tests may be needed.

Some of the tests that were done to diagnose the cancer or to find out the stage of the cancer may be repeated. Some tests will be repeated in order to see how well the treatment is working. Decisions about whether to continue, change, or stop treatment may be based on the results of these tests.

Some of the tests will continue to be done from time to time after treatment has ended. The results of these tests can show if your child's condition has changed or if the cancer has recurred (come back). These tests are sometimes called follow-up tests or check-ups.

Treatment of GIST

Treatment for children who have newly diagnosed tumors with changes in the KIT or PDGFR gene includes the following:

• Targeted therapy with a tyrosine kinase inhibitor (imatinib or sunitinib).

Treatment for children whose newly diagnosed tumors are SDH-deficient may include the following:

• Surgery to remove the tumor. More surgery may be needed if intestinal obstruction or bleeding occurs.
• Targeted therapy with a tyrosine kinase inhibitor (sunitinib).

Treatment of Recurrent GIST

Treatment of recurrent GIST in children may include the following:

• A clinical trial that checks a sample of the patient's tumor for certain gene changes. The type of targeted therapy that will be given to the patient depends on the type of gene change.
• A clinical trial of a new chemotherapy drug.