Signs and symptoms of gastrointestinal stromal tumors

Most gastrointestinal stromal tumors (GISTs) occur in the stomach or small intestine. These tumors may not cause any symptoms unless they are in a certain location or grow to a certain size.

The most common symptoms of GISTs are abdominal discomfort or pain, with bleeding into the intestinal tract. If the bleeding is fast enough, it can make bowel movements black and tarry. Slower bleeding may not change the color of bowel movements, but it can lead to anemia (low red blood cell counts). This can cause a person to feel tired and weak. If the tumor bleeds into the stomach, it may cause the patient to vomit blood.

Nausea, vomiting, loss of appetite, and weight loss can also occur. Tumors in the esophagus can cause problems with swallowing. In some cases a person may actually feel a growth (tumor) in his or her abdomen.

In some people the tumor may grow into the intestine and block it. This is called intestinal obstruction, and it causes severe abdominal pain and vomiting. Emergency surgery is often needed to treat the blockage.

Small tumors may not cause any symptoms. They are found accidentally when the doctor is looking for some other problem. These are often benign.

If there is a reason to suspect that you may have a GIST, the doctor will use one or more methods to find out if the disease is really present.

Medical history and physical exam

To learn your medical history, the doctor will ask you questions about symptoms and risk factors you may have. If you have one or more symptoms that suggest you have a GIST, the doctor will ask about signs and symptoms that might be caused by a mass in the esophagus, stomach, intestine, or rectum. A thorough physical exam may provide evidence of a GIST, such as a mass in the abdomen, or other health problems.

Imaging tests

Your doctor may order an imaging test to help find the cause of your symptoms.

Barium x-rays

For these studies (tests), a barium-containing solution is used to coat the lining of the esophagus, stomach, and intestines. This makes abnormalities of the lining easier to see on x-ray. These are sometimes useful in diagnosing GI tumors. They are least effective in finding small intestine tumors. You will probably have to fast starting the night before the test. If the colon is being examined, you may need to take laxatives and/or enemas to clean out the bowel the night before or the morning of the exam.

Barium swallow: This test (also known as an upper GI series) is used to examine the lining of the esophagus, stomach, and the first part of the small intestine. Patients getting this test drink a barium solution before the x-ray pictures are taken.

Small bowel follow through: This is a continuation of the barium swallow test that is sometimes used to look for problems in the small intestine. For this test, x-rays are taken at regular intervals over the course of a few hours as the barium passes through the intestines.

Enteroclysis: This procedure is another way to look at the small intestine. In this test, a thin tube is passed through the mouth or nose and through the stomach into the start of the small intestine. Barium is sent through the tube, along with a substance that creates more air in the intestines, causing them to expand. X-rays of the intestines are then taken. This test can give better images of the small intestine than a small bowel follow through, but it is also more uncomfortable.

Barium enema: This test (also known as a lower GI series) is used to look at the inner surface of the large intestine. For this test, the barium solution is given through the anus while the patient is lying on the x-ray table. When the colon is about half full of barium, the patient rolls over so the barium spreads throughout the colon. For a regular barium enema, x-rays are then taken. After the barium is put in the colon, air may be blown in to help push the barium toward the wall of the colon and better coat the inner surface. Then x-rays are taken. This is called an air- contrast barium enema (also known as double-contrast barium enema).

Barium x-rays are used less these days than before. In many cases they are being replaced by endoscopy -- where the doctor actually looks into the colon or stomach with a narrow fiber optic scope (see below).

Computed tomography

The computed tomography (CT) scan is an x-ray procedure that produces detailed, cross-sectional images of your body. Instead of taking one picture, like a standard x-ray, a CT scanner takes many pictures as it rotates around you. A computer then combines these into images of slices of the part of your body that is being studied.

Before any pictures are taken, you may be asked to swallow an oral contrast liquid. This helps outline your intestinal tract to make tumors easier to see. You may also receive an intravenous (IV) line so that a dye (IV contrast) can be injected. This can help better outline structures in your body.

The IV injection can cause some flushing (redness and warm feeling). Some people are allergic and get hives or, rarely, more serious reactions like trouble breathing and low blood pressure. Medicines can be given to prevent and treat any allergic reactions, so it is important for you to let the doctor know before the scan about any previous reactions you might have had to contrast material used for x-rays.

CT scans take longer than regular x-rays. You need to lie still on a table, and the part of your body being looked at is placed within the scanner, a cylinder-shaped machine that completely surrounds the table. The test is painless, but you may find it uncomfortable to hold still in certain positions for minutes at a time.

CT scans are useful in patients with GISTs to find the location and size of the tumor, as well as to see whether it has spread into the abdomen or the liver.

In some cases, CT scans can also be used to guide a biopsy needle precisely into a suspected cancer or metastatic lesion. However, because this can be risky when a GIST is involved (bleeding, possible increased risk of tumor spread), these types of biopsies are usually done only if the result might affect the decision on treatment. (For more information, see the information about biopsy below.)

Magnetic resonance imaging

Magnetic resonance imaging (MRI) scans use radio waves and strong magnets instead of x-rays. The energy from the radio waves is absorbed and then released in a pattern formed by the type of tissue and by certain diseases. A computer translates the pattern into a very detailed image of parts of the body. Not only does this produce cross-sectional slices of the body like a CT scanner, but it can also produce slices that are parallel with the length of your body. A contrast material might be injected just as with CT scans, but is used less often.

MRI scans are a little more uncomfortable than CT scans. They take longer -- often up to an hour. You have to lie inside a tube, which is confining and can upset some people with a fear of enclosed spaces (claustrophobia). Newer, "open" MRI machines can be easier to tolerate, but they are less available. The machine also makes buzzing and clicking noises that some people might find disturbing. Many places will provide ear plugs or headphones with music to block this noise out.

MRI scans are useful in GISTs to find the extent of the cancer in the abdomen, although usually CT scans are adequate. They are also useful in looking for return of cancer (recurrence) or spread (metastases) to distant organs, particularly in the brain or spine.

Positron emission tomography

Positron emission tomography (PET) scans have become one of the most useful tests for spotting GISTs. In PET scanning, low-level radioactive glucose (sugar) is injected into the patient's vein. Because cancer cells use sugar much faster than normal cells, the tumor takes up the radioactive material more quickly. A special camera can then be used to spot the radioactive areas in the body.

This test can be useful to find areas of cancer spread. PET scans are often used to find out if a drug treatment is working. The scan is usually obtained at least 4 weeks after starting the medication. If the drug is working, the tumor will stop taking up the radioactive glucose. If the tumor still takes up the glucose, your doctor may decide to change your drug treatment.

Some imaging machines combine a PET scanner with a CT scan to better pinpoint areas of tumor spread.

Endoscopy

These tests use a flexible lighted tube (endoscope) with a video camera on the end. The camera sends pictures to a video screen, so that the doctor can clearly see any masses (tumors) in the lining of the digestive organs. If abnormal areas are found, small pieces of tissue can be removed through the endoscope (biopsy). The tissue can be looked at under the microscope to find out if cancer is present and what kind of cancer it is.

When looking into the GI tract with an endoscope, the doctor may see only a bulge under the normally smooth surface if a GIST is present. This is because GIST tumors are often below the lining (mucosa) of the GI tract. This makes them harder to see with endoscopy than more common GI tract tumors. GISTs that are below the mucosa (submucosal) are also harder to biopsy through the endoscope. As a result, only about half of GISTs are diagnosed before surgery.

If the tumor breaks through the lining of the GI tract and is easy to see, there is a greater chance that the GIST is cancerous (malignant).

Upper endoscopy (also known as esophogogastroduodenoscopy or EGD): patients are given medicines to make them sleepy (sedated). Then the endoscope is passed down through the mouth to show the esophagus, stomach, and first part of the small bowel.

Colonoscopy (also known as a lower endoscopy): a type of endoscope known as a colonoscope is inserted through the anus and up into the colon. This allows the doctor to see the lining of the entire rectum and colon. To get a good look at the inside of the colon, it must be empty and cleaned out before the test. This often means using a strong laxative the night before. Sometimes enemas are also needed the morning of the procedure to make sure the bowels are empty. You will be given intravenous (IV; into a vein) medicine to make you feel relaxed and sleepy during the procedure. A colonoscopy may be done in a hospital outpatient department, in a clinic, or in a doctor's office. It usually takes 15 to 30 minutes, although it may take longer if a tumor is seen and/or a biopsy taken.

Capsule endoscopy: Unfortunately, neither upper nor lower endoscopy can reach all areas of the small intestine, Capsule endoscopy is one way to look at the small intestine. This procedure does not actually use an endoscope. Instead, the patient swallows a capsule (about the size of a large vitamin pill) that contains a light source and a very small camera. Like any other pill, the capsule goes through the stomach and into the small intestine. As it travels (usually over the course of about 8 hours), it takes thousands of pictures. These images are transmitted electronically to a device worn around the person's waist. The pictures can then be downloaded onto a computer, where the doctor can view them as a video. The capsule passes out of the body during a normal bowel movement and is discarded. This test requires no sedation -- the patient can just continue normal daily activities as the capsule travels through the GI tract. This technique is fairly new, and the best way to use it is still being studied.

Double balloon enteroscopy: This is another way to look at the small intestine. The small intestine is too long (20 feet) with too many curves to be examined well with regular endoscopy. This method gets around these problems by using a special endoscope that is made up of 2 tubes, one inside the other. First the inner tube, which is an endoscope, goes forward about a foot, and then a balloon at its end is inflated to anchor it. Then the outer tube goes forward to near the end of the inner tube and it is then anchored in place with a balloon. This process keeps being repeated over and over, letting the doctor see the intestine a foot at a time. The procedure is done after the patient is given drugs to make him or her sleepy. The main advantage of this test over capsule endoscopy is that the doctor can take a biopsy if something abnormal is seen.

Endoscopic ultrasound

This test uses an endoscope with a small ultrasound probe on the end. Since the probe is on the end of an endoscope, it can be placed very close to (or on top of) the tumor. The probe gives off high-frequency sound waves and then detects the sound wave echoes that bounce off tissues of the digestive tract wall. A computer then translates the pattern of echoes into an image of the area being looked at.

Endoscopic ultrasound can be used to find the precise location of the GIST and to determine its size. It is useful in finding out how deeply a tumor has grown into the wall of the digestive tract (esophagus, stomach, intestine, or rectum). The test can also help predict whether the tumor has spread to lymph nodes or has started growing into other tissues nearby. In some cases it may be used to help guide a biopsy (see below).

Biopsy

Even if a mass is found on a barium x-ray or CT scan, these imaging tests cannot tell if the mass is a GIST, some other type of tumor (benign or cancerous), or some other condition (like an infection). The only way to know what it is for sure is to remove cells from the abnormal area and look at them under a microscope. This procedure is called a biopsy. There are several ways to take a sample from a GI tract tumor.

Endoscopic biopsy

Biopsy samples can be obtained through the endoscope. When a tumor is found, the doctor can operate a biopsy forceps (pincers or tongs) through the tube to take a small sample of the tumor. Even though the sample will be very small, doctors can usually make an accurate diagnosis. About half the time, the biopsy will not get the cancer because it grows underneath the lining of the intestine or stomach. (The biopsy forceps can't go deep enough.)

Bleeding from a GIST after a biopsy is rare but can be a serious problem. If this occurs, doctors can sometimes inject drugs that constrict blood vessels through the endoscope into the tumor to stop the bleeding.

Fine needle biopsy

In some cases, a biopsy sample is obtained with a thin, hollow needle. The doctor places this needle into the tumor while being guided by imaging tests such as a CT scan or endoscopic ultrasound. These types of biopsies must be done carefully and are usually done only if they will help determine treatment options, because doctors are concerned they may cause bleeding or possibly increase the risk of cancer spreading.

Surgical biopsy

If a sample can't be obtained from an endoscopic or needle biopsy or if the result wouldn't affect treatment options, a doctor may recommend waiting until surgery to get a sample of the tumor. This is done in an operation called a laparotomy, where the doctor creates an opening in the abdomen to reach and remove the tumor directly.

Testing the biopsy sample

Once a tumor sample is obtained, a doctor who specializes in lab tests (a pathologist) looks at it under a microscope. Although the pathologist may suspect that a tumor is a GIST, he or she can't be sure without a special test called immunohistochemistry.

In this test, a part of the sample is treated with special manmade antibodies that will attach only to the KIT protein (also called CD117). The antibodies cause color changes if the KIT protein is present, which can be seen under a microscope. Because most GIST cells contain this substance but cells of most other types of cancer do not, this test can be useful in determining whether a GI tumor is a GIST or not. If the tumor cells do not contain KIT, they will be checked to see if they have the protein made by the PDGFRA gene. This is found in about 5% of GISTs.

Blood tests

Your doctor may order some blood tests if he or she thinks you may have a GIST. A blood count can tell if you are anemic (have a low red blood cell count). Some people with GIST may become anemic because of bleeding from the tumor.

Other blood tests can measure your liver function. If the results of theses tests are abnormal, it may mean that the GIST has spread to your liver.

There are no blood tests that can detect GIST cancer cells in the blood. These tumors do not release any known substances in the blood that can be used as markers to measure the response of a GIST to treatment.

Last Medical Review: 05/11/2009
Last Revised: 05/11/2009