Gastrointestinal Stromal Tumor - GISTLast Updated: August 03, 2011 This section has been reviewed and approved by the Cancer.Net Editorial Board, 10/10 Overview
A tumor begins when normal cells begin to change and grow uncontrollably. A tumor can be benign (noncancerous) or malignant (cancerous, meaning it can spread to other parts of the body). A gastrointestinal stromal tumor (GIST) is a type of tumor that occurs in the gastrointestinal (GI or digestive) tract, including the esophagus, stomach, gallbladder, liver, small intestine, colon, rectum, and lining of the gut. GISTs are different from other types of gastrointestinal tumors because of the type of tissue in which they start. Originally, GISTs were thought to be either muscle or nerve tumors, but recent research points to GISTs starting in cells found in the walls of the GI tract, called interstitial cells of Cajal (ICC); these cells send signals to the GI tract to help move food and liquid through the system. GISTs belong to a group of cancers called soft tissue sarcoma. Soft tissue sarcomas are a group of cancers that develop in the tissues that support and connect the body, and the sarcoma cells resemble the cells that hold the body together, including fat cells, muscles, nerves, tendons, joints, blood vessels, or lymph vessels. It is important to note that GISTs can be either benign or malignant. Sometimes it may be hard for the doctor to tell immediately whether a GIST is likely to come back after treatment. As a result, the doctor will look at many factors to determine the best treatment, including the size of the tumor, whether it has already spread, how many dividing cells there are, and the tumor’s location. Find out more about basic cancer terms used in this section. Looking for More of an Overview? If you would like additional introductory information, explore the following related item on Cancer.Net:
Or, choose “Next” (below, right) to continue reading this detailed section. Statistics
Each year, approximately 3,300 to 6,000 adults in the United States will be diagnosed with a GIST. The most common locations in the body are in the stomach (60% of people with GIST) and small intestine (30% of people with GIST). The remaining types of GISTs mostly start in the rectum, colon, and esophagus. GIST most often occurs in people older than 50, and GIST is slightly more common in men than in women. Statistics should be interpreted with caution. Estimates are based on data from thousands of people with this type of tumor in the United States each year, but the actual risk for a particular individual may differ. It is not possible to tell a person how long he or she will live with GIST, though most people with GIST, even those with advanced disease, survive for years. Learn more about understanding statistics. Source: American Cancer Society. Risk Factors
A risk factor is anything that increases a person’s chance of developing a tumor. Although risk factors can influence the development of a tumor, most do not directly cause the disease. Some people with several risk factors never develop a tumor, while others with no known risk factors do. However, knowing your risk factors and communicating them to your doctor may help you make more informed lifestyle and health care choices. The majority of GISTs develop for no known reason, called sporadic. In fact, researchers have identified only a single risk factor for GIST: Family history. The only known risk factor for GIST is family history of the disease, when there is a small increase in an individual’s personal risk of developing GIST. Hereditary syndromes that can raise the risk of GIST include neurofibromatosis Type 1 (NF1) and Carney-Stratakis Dyad. Researchers continue to look for specific genes and other syndromes that may be related to the development of GIST. However, hereditary GIST is extremely rare. Because no preventable risk factors have been found, there is no way to keep from getting GIST. Symptoms
People with GIST may experience many different symptoms or signs. Sometimes, people with GIST do not show any of these symptoms. Or, these symptoms may be caused by a medical condition that is not a tumor. If you are concerned about a symptom or sign on this list, please talk with your doctor. GISTs are not usually found at an early stage because they often do not cause specific symptoms. When symptoms do occur, they may be vague and can include:
Diagnosis
Doctors use many tests to diagnose a tumor and find out if it is cancerous and, if so, if it has metastasized (spread). Some tests may also determine which treatments may be the most effective. For most types of tumors, a biopsy is the only way to make a definitive diagnosis. If a biopsy is not possible, the doctor may suggest other tests that will help make a diagnosis. Imaging tests may be used to find out whether the cancer has metastasized. Your doctor may consider these factors when choosing a diagnostic test:
In addition to a physical examination, the following tests may be used to diagnose GIST or determine the best treatment: Computed tomography (CT or CAT) scan. A CT scan creates a three-dimensional picture of the inside of the body with an x-ray machine. A computer then combines these images into a detailed, cross-sectional view that shows any abnormalities or tumors. Sometimes, a contrast medium (a special dye) is injected into a vein to provide better detail. For patients with GIST, the CT scan is the most commonly used diagnostic tool. A CT scan can help doctors determine whether the cancer has spread to the liver. Fecal occult blood test. This test detects occult (hidden) blood in the stool, which can be caused by cancer in the GI tract. A small amount of stool is placed on a plastic slide or special paper and is tested in the doctor's office or a laboratory. X-ray. An x-ray is a picture of the inside of the body. For instance, a chest x-ray can help doctors determine if the cancer has spread to the lungs. X-rays may be taken of the esophagus and stomach, which are referred to as the upper GI tract. This procedure is also called a barium swallow, because the x-rays are taken after a patient drinks a substance called barium, which outlines the GI tract on the x-ray and helps the doctor see a tumor or other abnormal areas. In a barium enema, the doctor looks at the lining of the colon and rectum on the x-ray after the barium is given through the anus. Endoscopy. This test allows the doctor to see the inside of the stomach. The patient may be sedated, and the doctor inserts a thin, lighted tube called a gastroscope through the mouth, down the esophagus, and into the stomach and small bowel. If abnormal areas are found, the doctor can remove a sample of tissue and check it for evidence of cancer. Endoscopic ultrasound. This test is similar to an endoscopy, but the gastroscope has a small ultrasound probe on the end that uses sound waves to create an image of the stomach. The ultrasound image helps doctors determine if or how far the cancer has spread into the stomach and nearby tissues. Magnetic resonance imaging (MRI). An MRI uses magnetic fields, not x-rays, to produce detailed images of the body. A contrast medium may be injected into a patient’s vein to create a clearer picture. Positron emission tomography (PET) scan. A PET scan is a way to create pictures of organs and tissues inside the body. A small amount of a radioactive substance is injected into a patient’s body. This substance is absorbed mainly by organs and tissues that use the most energy. Because cancer tends to use energy actively, it absorbs more of the radioactive substance. A scanner then detects this substance to produce images of the inside of the body. PET scans are often used to add to the information from the CT scan, MRI, and physical examination, and may be used to show early growth of the disease (called PET flare), or to measure how well treatment is working. Biopsy. It is very important that a patient is seen by a team of medical and surgical oncologists experienced in the treatment of GIST before any surgery or biopsy are performed. A biopsy is the removal of a small amount of tissue for examination under a microscope. Other tests can suggest that cancer is present, but only a biopsy can make a definite diagnosis. The sample removed from the biopsy is analyzed by a pathologist (a doctor who specializes in interpreting laboratory tests and evaluating cells, tissues, and organs to diagnose disease). The type of biopsy performed will depend on the location of the tumor. With GIST, the patient may still be monitored even if the biopsy results do not indicate cancer, as a biopsy for GIST is not always definitive. In some instances, an entire tissue mass or an organ will be removed to make a diagnosis. Learn more about what to expect when having common tests, procedures, and scans. Find out more about common terms used during a diagnosis of cancer. Staging
Staging is a way of describing a tumor, such as where it is located, whether it has spread, and if it is affecting the functions of other organs in the body. Doctors use diagnostic tests to determine the tumor's stage, so staging may not be complete until all the tests are finished. Knowing the stage helps the doctor to decide what kind of treatment is best and can help predict a patient's prognosis (chance of recovery). There are different stage descriptions for different types of cancers. One tool that doctors use to describe the stage of other types of cancer is the TNM system. This system uses three criteria to judge the stage of the cancer: the tumor itself (T), the lymph nodes (N) around the tumor, and if the tumor has spread to other parts of the body (metastasis, M). The results are combined to determine the stage of cancer for each person. However, while TNM staging does exist for GIST, most experts do not consider its use standard practice. Instead, doctors look at different factors to help determine a patient’s prognosis and the specific risk of how aggressive an individual tumor will be, such as low risk, intermediate risk, or high risk. This means how quickly it may grow and the likelihood of the tumor recurring (coming back), specifically after surgery. Common factors that doctors use are the size of the tumor, the mitotic count (the actual number of dividing cells), and the location of the tumor. Treatment
The treatment of GIST depends on the size and location of the tumor, whether it looks aggressive under the microscope, if it is cancerous, whether the cancer has spread, and the person’s overall health. In many cases, a team of doctors will work with the patient to determine the best treatment plan. This section outlines treatments that are the standard of care (the best treatments available) for this specific type of cancer. Patients are also encouraged to consider clinical trials as a treatment option when making treatment plan decisions. A clinical trial is a research study to test a new treatment to prove it is safe, effective, and possibly better than standard treatment. Your doctor can help you review all treatment options. For more information, see the Clinical Trials section. Descriptions of the most common treatment options for GIST are listed below. Surgery For patients with localized GIST, surgery is the standard of care and should be performed whenever possible. A surgical oncologist is a doctor who specializes in treating cancer using surgery. The goal of surgery is to completely remove the tumor. Sometimes, the tumor may be large or spread into nearby organs. In many of these instances, a drug called imatinib (see below) will be given before surgery. The surgeon will most likely still try to remove the entire tumor in an effort to reduce the risk that the tumor will recur or block the GI tract. In order to remove the entire tumor, it is possible that the surgeon may have to remove parts of nearby organs, depending on the location of the tumor. The removal of lymph nodes is not generally needed in the treatment of a GIST because it does not often spread to the lymph nodes. Learn more about cancer surgery. Targeted therapy Targeted therapy is a treatment that targets specific genes, proteins, or the tissue environment that contributes to cancer growth and survival. In 2002, the U.S. Food and Drug Administration (FDA) approved imatinib (Gleevec) for the treatment of GIST. Imatinib is a tyrosine kinase inhibitor, and it is the drug of choice in treating GIST. Since this drug has become available, the prognosis for patients with GIST has improved considerably. It is usually given as either the only treatment or in combination with surgery (before or after surgery) and is given for a long time. For patients with GIST that has spread to other parts of the body, imatinib is taken for the rest of the patient’s life to help control the tumor. The usual dose of imatinib is 400 milligrams (mg) daily. In some patients the dose can be raised to 800 mg daily, especially in patients that have an exon 9 genetic mutation (change in a part of the KIT gene; this mutation may occur when the tumor starts in the small bowel or colon). The most common side effects of imatinib are fluid accumulation, rash, nausea, and minor muscle aches. Serious but relatively rare side effects include bleeding and chemical inflammation of the liver. Some side effects from imatinib get better over time. So making a decision to stop treatment because of side effects should be considered carefully. Sunitinib (Sutent), like imatinib, is a tyrosine kinase inhibitor called an anti-angiogenic that stops tumors from creating new blood vessels. It was approved in 2006 by the FDA for treating GIST when the tumor continues to grow even after treatment with imatinib, or when imatinib cannot be given. Learn more about targeted treatments. The medications used to treat cancer are continually being evaluated. Talking with your doctor is often the best way to learn about the medications prescribed for you, their purpose, and their potential side effects or interactions with other medications. Learn more about your prescriptions by using searchable drug databases. Radiation therapy Radiation therapy is the use of high-energy x-rays or other particles to kill cancer cells. A doctor who specializes in giving radiation therapy to treat cancer is called a radiation oncologist. The most common type of radiation treatment is called external-beam radiation therapy, which is radiation given from a machine outside the body. A radiation therapy regimen (schedule) usually consists of a specific number of treatments given over a specific time. In GIST, radiation therapy is not often used, as it is unclear whether the tumor responds to this treatment. However, it may be used as a palliative treatment (treatment used to reduce pain, control symptoms, or make a patient more comfortable) to relieve pain or stop bleeding. Radiation therapy may damage healthy cells as well as cancerous cells. Side effects from radiation therapy include tiredness, mild skin reactions, upset stomach, and loose bowel movements. Most side effects go away soon after treatment is finished. Learn more about radiation therapy. Chemotherapy Chemotherapy is the use of drugs to kill cancer cells. Chemotherapy is not effective in treating GIST; therefore, it should not be used. Find out more about common terms used during treatment. Clinical Trials Resources
Doctors and scientists are always looking for better ways to treat patients with GIST. A clinical trial is a way to test a new treatment to prove that it is safe, effective, and possibly better than a standard treatment. The clinical trial may be evaluating a new drug, a new combination of existing treatments, a new approach to radiation therapy or surgery, or a new method of treatment or prevention. Patients who participate in clinical trials are among the first to receive new treatments before they are widely available. However, there is no guarantee that the new treatment will be safe, effective, or better than a standard treatment. Patients decide to participate in clinical trials for many reasons. For some patients, a clinical trial is the best treatment option available. Because standard treatments are not perfect, patients are often willing to face the added uncertainty of a clinical trial in the hope of a better result. Other patients volunteer for clinical trials because they know that finding new drugs and other therapies is the only way to make progress in treating GIST. Even if they do not benefit directly from the clinical trial, their participation may benefit future patients with GIST. Sometimes people have concerns that, by participating in a clinical trial, they may receive no treatment by being given a placebo or a “sugar pill”. The use of placebos in cancer clinical trials is rare. When a placebo is used in a study, it is done with the full knowledge of the participants, and the patients are often offered the experimental drug, if the tumor grows while they are on placebo. Find out more about placebos in cancer clinical trials. To join a clinical trial, patients must participate in a process known as informed consent. During informed consent, the doctor should list all of the patient’s options, so the person understands how the new treatment differs from the standard treatment. The doctor must also list all of the risks of the new treatment, which may or may not be different from the risks of standard treatment. Finally, the doctor must explain what will be required of each patient in order to participate in the clinical trial, including the number of doctor visits, tests, and the schedule of treatment. Learn more about clinical trials, including patient safety, phases of a clinical trial, deciding to participate in a clinical trial, questions to ask the research team, and links to find clinical trials. For specific topics being studied for GIST, learn more in the Current Research section. Side Effects
A tumor and its treatment can cause a variety of side effects. However, doctors have made major strides in recent years in reducing pain, nausea and vomiting, and other physical side effects of treatments. Many treatments used today are less intensive but as effective as treatments used in the past. Doctors also have many ways to provide relief to patients when such side effects do occur. Fear of treatment side effects is common after a diagnosis of GIST, but it may be helpful to know that preventing and controlling side effects is a major focus of your health care team. Before treatment begins, talk with your doctor about possible side effects of the specific treatments you will be receiving. The specific side effects that can occur depend on a variety of factors, including the type of tumor, its location, the individual treatment plan (including the length and dosage of treatment), and the person’s overall health. Ask your doctor which side effects are most likely to happen (and which are not), when side effects are likely to occur, and how they will be addressed by the health care team if they do happen. Also, be sure to communicate with the doctor about side effects you experience during and after treatment. Learn more about the most common side effects of cancer and different treatments, along with ways to prevent or control them. In addition to physical side effects, you may experience psychosocial (emotional and social) effects as well. Learn more about the importance of addressing such needs, including concerns about managing the cost of your medical care. Learn more about late effects or long-term side effects by reading the After Treatment section or talking with your doctor. After Treatment
Talk with your doctor about developing a follow-up care plan after your initial treatment for GIST. This plan will include regular physical examinations and medical tests to monitor your recovery over the coming months and years. ASCO offers cancer treatment summary forms to help keep track of the treatment you received and develop a survivorship care plan once treatment is completed. A person treated for GIST is typically seen by the doctor every three to six months for up to five years and then annually after that. This follow-up care is important because there is always a risk that the tumor could recur, even after extensive surgery. People recovering from GIST are encouraged to follow established guidelines for good health, such as maintaining a healthy weight, not smoking, eating a balanced diet, and having recommended cancer screening tests. Talk with your doctor to develop a plan that is best for your needs. Moderate physical activity can help rebuild your strength and energy level. Your doctor can help you create an appropriate exercise plan based upon your needs, physical abilities, and fitness level. Learn more about healthy living. Find out more about common terms used after treatment is complete. Current Research
Research for GIST is ongoing. The following advances may still be under investigation in clinical trials and may not be approved or available at this time. Always discuss all diagnostic and treatment options with your doctor. Personalized medicine. Recent studies have shown that depending on genetic findings (specific gene mutations), some patients may need higher doses of imatinib to best control the tumor. Currently this testing is being offered within and outside of clinical trials. Also, because the exact type of gene mutation in GIST helps determine how well treatment with imatinib will work, testing each patient for genetic mutations can help doctors target the specific mutation present in the tumor. This may fine-tune the most appropriate treatment to be given in the early stage of the tumor. New drugs. Researchers are examining whether the drugs nilotinib (Tasigna), approved for the use in chronic myeloid leukemia (CML), and sorafenib (Nexavar) are effective in some patients with GIST that does not respond to imatinib and sunitinib. To find clinical trials specific to your diagnosis, talk with your doctor or search online clinical trial databases now. Questions to Ask the Doctor
Regular communication with your doctor is important in making informed decisions about your health care. Consider asking the following questions of your doctor: General questions:
Questions to ask before surgery:
Questions about imatinib mesylate (Gleevec):
Questions to ask before radiation therapy:
After treatment, including surgery:
Patient Information Resources
In addition to Cancer.Net, there are other sources of information about this type of tumor available online. Cancer.Net maintains a list of national, not-for-profit organizations that may be helpful in finding additional information, services, and support. As always, be sure to talk with your doctor about questions you may have about information you find about this disease. View organizations that offer information on this specific type of tumor. |
