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This information is about a specific type of soft tissue sarcoma known as GIST (gastrointestinal stromal tumour). It should ideally be read with our general information about soft tissue sarcomas.
Gastrointestinal stromal tumours (GISTs) belong to a group of cancers called soft tissue sarcomas.
Sarcomas are cancers that develop in the supporting or connective tissues of the body (such as muscle, fat, nerves, blood vessels, bone and cartilage).
Soft tissue sarcomas are rare. Approximately 2,200 people will be diagnosed with a sarcoma each year in the UK.
GISTs are a rare type of soft tissue sarcoma, so they are very rare indeed. About 3 in 5 GISTs occur in the stomach, but they can occur anywhere along the length of the digestive system from the gullet (oesophagus) to the anus (back passage). They start in the cells of the stroma. The stroma is the connective tissue that supports the organs involved in digesting food. The digestive system is often called the gastrointestinal tract.
The exact causes of GISTs are unknown, and research is ongoing to try and find out as much as possible about this condition. However, scientists have discovered that most GIST cells have an enzyme disorder. A particular chemical (enzyme) called tyrosine kinase is responsible for sending signals inside the cell, that stimulate the cell to grow and divide. The tyrosine kinase enzyme can trigger the growth of some GIST tumour cells.
Most people who have been diagnosed with GIST do not have a family history of the condition. However, there are very rare cases where several family members have been diagnosed with GIST. People with a condition called neurofibromatosis (NF) have a slightly increased risk of developing a GIST. GISTs rarely occur in people younger than 50.
People with an early-stage GIST often do not have any symptoms of the disease. Most GISTs are diagnosed after a person develops symptoms. These may include:
If you notice any of the above, contact your GP, but remember that these symptoms can also be caused by other conditions.
Usually you begin by seeing your GP who will examine you and refer you to a hospital specialist.
At the hospital, the doctor will ask you about your general health and any previous medical problems. They will also examine you and take blood samples to check your general health and that your liver is working properly. The following tests may also be carried out:
Endoscopy This is the most common test used to diagnose any problems in the stomach and oesophagus (gullet). Before an endoscopy, your stomach has to be empty, so you will be asked not to eat or drink anything for at least four hours beforehand. Once you are lying comfortably on the couch you will be given a sedative, usually into a vein in your arm. This will make you feel sleepy and reduce any discomfort during the test. A local anaesthetic is then sprayed onto the back of your throat and the doctor passes an endoscope (a flexible tube containing a light and camera) down the gullet into the stomach. Photographs are taken of the stomach and a small sample of cells (biopsy) can be taken, for examination under a microscope.
Endoscopic ultrasound Sometimes the endoscopy tube has an ultrasound probe at the end of it. This allows an ultrasound scan of the stomach to be done. An ultrasound uses sound waves to build up a picture of the inside of the body.
An endoscopy can be uncomfortable but it is not painful. After a few hours the effects of the sedative should have worn off and you will be able to go home. You should not drive for several hours afterwards. It is a good idea to arrange for someone to travel home with you. Some people have a sore throat after their endoscopy. This is normal and should disappear after a couple of days.
Biopsy If the doctor strongly suspects a diagnosis of cancer, they will take biopsies (samples of tissue) during the endoscopy. When the cells are looked at under a microscope, the pathologist will be able to tell whether they are benign (not cancerous) or malignant (cancerous). If a sarcoma is diagnosed, further tests may be done on the sample to try to find out exactly what type of sarcoma it is.
One of the things the pathologist will look for when diagnosing a GIST is whether there are detectable amounts of tyrosine kinase. If high levels of tyrosine kinase are present, this helps to identify the tumour as a GIST.
Ultrasound scan Sound waves are used to make up a picture of the abdomen and surrounding organs. The scan is done in the hospital scanning department. You will be asked not to eat, and to drink clear fluids only (nothing fizzy or milky) for 4–6 hours before the scan. Once you are lying comfortably on your back, a gel is spread onto your abdomen. A small device like a microphone is then rubbed over the area. The sound waves are converted into a picture using a computer. The test is completely painless and takes about 15–20 minutes.
CT (computerised tomography) scan A CT scan takes a series of x-rays that builds up a three-dimensional picture of the inside of the body. The scan is painless and takes from 10–30 minutes. CT scans use a small amount of radiation, which is very unlikely to harm you and will not harm anyone you come into contact with. You will be asked not to eat or drink for at least four hours before the scan.
You may be given a drink or an injection of dye that allows particular areas to be seen more clearly. For a few minutes this may make you feel hot all over. If you are allergic to iodine or have asthma, you could have a more serious reaction to the injection, so it is important to let your doctor know beforehand.
Most people are able to go home fairly soon as their scan is over.
MRI (magnetic resonance imaging) scan This test is similar to a CT scan, but uses magnetism instead of x-rays to build up cross-sectional pictures of your body. During the test you will be asked to lie very still on a couch inside a large metal cylinder that is open at both ends. The whole test may take up to an hour. It can be slightly uncomfortable and some people feel a bit claustrophobic during the scan. It is very noisy, but you will be given earplugs or headphones to wear. A two-way intercom allows you to talk with the people controlling the scanner. If you have any metal implants (such as surgical clips, pacemakers, metal in the eye from previous accidents or trauma) it will not be possible for you to have this test.
PET (Positron Emission Tomography) scan A PET scan uses low-dose radioactive sugar to measure the activity of cells in different parts of the body. A very small amount of a mildly radioactive substance is injected into a vein, usually in your arm. A scan is then taken a couple of hours later. Areas of cancer are usually more active than surrounding tissue and show up on the scan.
The stage of a cancer is a term used to describe its size and whether it has spread beyond its original site. Knowing the particular type and the stage of the cancer helps the doctors to decide on the most appropriate treatment.
Generally, sarcomas are divided into four stages, from 'small and localised' (stage 1) to 'spread into surrounding structures' (stages 2 or 3) or 'spread to other parts of the body' (stage 4). If the cancer has spread to distant parts of the body this is known as secondary or metastatic cancer.
As GISTs are very rare there is no established staging system.
Recurrence means that a soft tissue sarcoma has come back after it was first treated. It may come back in the tissues where it first started (local recurrence) or it may come back in another part of the body (metastasis).
The treatment for GIST depends on a number of factors, including your general health and the size and position of the tumour. The results of your tests will enable your doctor to discuss with you the best treatment for you. Because GISTs are rare cancers, you should always be referred for treatment at a specialist unit; where a team of specialist doctors work together. You may have to travel to a hospital outside your area for this.
Before you have any treatment, your doctor will give you full information about what it involves and explain the aims of the treatment to you. They will usually ask you to sign a form saying that you give permission (consent) for the hospital staff to give you the treatment. No medical treatment can be given without your consent.
Treatment can be given for different reasons and the potential benefits will vary depending upon the individual situation. If you have been offered treatment that aims to cure your cancer, deciding whether to have the treatment may not be difficult. However, if a cure is not possible and the treatment is to control the cancer for a period of time, it may be more difficult to decide whether or not to go ahead.
If you feel that you can't make a decision about treatment when it is first explained to you, you can always ask for more time to decide.
You are free to choose not to have the treatment and the staff can explain what may happen if you do not have it. You don't have to give a reason for not wanting to have treatment, but it can be helpful to let staff know your concerns so that they can give you the best advice.
The most common treatment for GIST is surgery to remove the tumour. If the GIST has begun to spread, it may sometimes also be possible to remove the secondary tumours.
If you had part or most of your stomach removed, you may have some difficulties with eating afterwards. Specialist dietitians can give you advice and support.
Chemotherapy and radiotherapy aren't used to treat GISTs as they don't work well for this type of cancer.
In order to grow, cancer cells need to receive chemical 'signals' to tell them to divide and make new cells. Growth inhibitors block these signals and affect the cancer's ability to grow.
There are different types of growth inhibitors. The drug imatinib (Glivec®) works by blocking tyrosine kinase enzymes that GISTs need in order to grow. It is therefore known as a tyrosine kinase inhibitor and is effective in treating GISTs.
The National Institute for Health and Clinical Excellence (NICE), which advises doctors on new drugs and treatments, recommends that imatinib should be the first treatment choice for people with a GIST that can't be completely removed with surgery or has begun to spread. The treatment is continued as long as it is working. Sometimes imatinib can shrink the GIST, so that it can then be removed surgically.
A different type of growth inhibitor called sunitinib (Sutent®) may sometimes be used if imatinib doesn't work or if it stops working. Sunitinib is a multikinase inhibitor and it works in a similar way to imatinib, by blocking the chemical signals within the cancer cell. Although sunitinib is licensed and can be prescribed in the UK, it has not been assessed by NICE and may not be available on the NHS.
Research into treatments for GIST is continuing and advances are being made. Cancer doctors use clinical trials to assess new treatments.
You may be asked to take part in a clinical trial. If you decide to take part in a trial, your doctor must discuss the treatment with you so that you have a full understanding of the trial and what it means to take part. You may decide not to take part or to withdraw from a trial at any stage. You will then receive the best standard treatment available.
The need for practical and emotional support will vary from person to person and may depend on the treatment you receive and any side effects the treatment may cause. Your specialist will inform you of any potential side effects and how to deal with them before you agree to treatment.
Many different emotions may affect you. Anger, guilt, anxiety and fear are some of the most common feelings that people have. You may find yourself tearful, restless and unable to sleep. You may have feelings of hopelessness and depression. These are all normal reactions, but it is often difficult and distressing to admit to them.
You do not have to cope with these feelings on your own and there are people available to help you. You may also find it helpful to talk to your family and friends about how you feel. Some hospitals have their own emotional support services with specially-trained staff, and some of the nurses on the ward will have received training in counselling. Some people feel more comfortable talking to a counsellor outside the hospital environment or to a religious leader. Cancerbackup can put you in touch with counselling services in your area.
This section has been compiled using information from a number of reliable sources, including:
For further references, please see the general bibliography.
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