Gastrointestinal stromal tumours (GISTs)

A gastrointestinal stromal tumour (GIST) is a type of soft tissue sarcoma that develops in the digestive tract. The digestive tract is the hollow tube that runs from the gullet (oesophagus) to the anus (back passage). Most GISTs begin in the stomach or small bowel, but they can develop anywhere along the digestive tract.

GISTs are rare cancers. Around 900 people in the UK are diagnosed with a GIST each year. We don't yet know what causes them.

Surgery to remove the cancer is usually the main treatment for GIST. Growth inhibitors may also be used to treat GISTs. Growth inhibitors stop cancer cells from growing by blocking signals. They are a drug treatment that’s taken as a tablet.

Research into treatments for GIST is ongoing and advances are being made. Cancer doctors use clinical trials to assess new treatments, so your doctor may ask you to take part in a clinical trial.

After your treatment, you will have regular check-ups at the hospital. It’s important to let your doctor know if you have new symptoms between appointments.

What are gastrointestinal stromal tumours (GISTs)?

Gastrointestinal stromal tumours (GISTs) are rare cancers. About 900 people in the UK are diagnosed with a GIST each year. They are most common in people aged 50–60 and are rare in people younger than 40.

GISTs belong to a group of cancers called soft tissue sarcomas. These are cancers that develop in the supporting or connective tissues of the body such as muscle, fat, nerves, blood vessels, bone and cartilage.

Most GISTs begin in the stomach or small bowel, but they can occur anywhere along the length of the digestive tract. The digestive tract is the hollow tube that runs from the gullet (oesophagus) to the anus (back passage).

Diagram of the digestive tract
Diagram of the digestive tract

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The walls of the digestive tract are made up of layers of muscle. GISTs start in cells that sit in between the muscle layers. These are sometimes called 'pacemaker' cells. They send signals to the muscles to push food and liquid through the digestive tract.


Causes and possible risk factors of GISTs

We don't yet know what causes GISTs. Most people who have a GIST don't have a family history of the condition. But there are very rare cases where several family members have been diagnosed with a GIST.

People with a condition called neurofibromatosis (NF) have a slightly increased risk of developing a GIST.


Signs and symptoms of a GIST

The symptoms you have will depend on the size of your GIST and where it is in your digestive tract. Symptoms may include:

  • tummy (abdominal) discomfort or pain
  • blood in the stools (bowel motions) or vomit
  • anaemia (low level of red blood cells)
  • a painless lump in the abdomen
  • being sick (vomiting)
  • fatigue (tiredness and a feeling of weakness)
  • a high temperature (fever) and sweating at night
  • weight loss.


How GISTs are diagnosed

Usually, you will 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 examine you and take blood samples to check your general health. The following tests may also be carried out:

Ultrasound scan

An ultrasound uses sound waves to produce an image of the inside of the tummy (abdomen). Once you're lying down comfortably, a gel is spread onto your tummy. The person doing the scan moves a small device like a microphone over the area. The scan is painless and takes about 15–20 minutes.

Endoscopy

The doctor will pass a thin, flexible tube called an endoscope into your mouth, down your gullet and into your stomach and small bowel. The endoscope has a light and camera at the end. This allows your doctor to see any abnormal areas. You may also have samples of tissue (biopsies) taken. These are sent to a laboratory to be tested.

An endoscopy can be uncomfortable but is not usually painful. You may have a sore throat after an endoscopy. This usually gets better after a couple of days.

Endoscopic ultrasound

An endoscopic ultrasound may be used to show the size and position of the tumour. It produces a picture of your stomach and the surrounding area. It’s done using an endoscope with an ultrasound probe at the end.

Biopsy

You may have samples of tissue (biopsies) taken from your tumour. They will be examined under a microscope.

A special test is done on the biopsy to look for a protein called KIT (CD117). Most GIST cells have this protein.

If you are going to have surgery to remove your tumour, you may not have a biopsy taken before your operation. Instead, the tumour will be sent to the laboratory after the operation for tests to confirm that it’s a GIST.

What happens in a CT scan?

A CT scan takes a series of x-rays, which build up a three-dimensional picture of the inside of the body. The scan takes 10–30 minutes and is painless. It uses 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.

CT scan
CT scan

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You may be given a drink or injection of a dye, which allows particular areas to be seen more clearly. This may make you feel hot all over for a few minutes. It’s important to let your doctor know if you are allergic to iodine or have asthma, because you could have a more serious reaction to the injection.

You’ll probably be able to go home as soon as the scan is over.

MRI scan

This test uses magnetism to build up a detailed picture of areas of your body. The scanner is a powerful magnet so you may be asked to complete and sign a checklist to make sure it's safe for you. The checklist asks about any metal implants you may have, such as a pacemaker, surgical clips, bone pins, etc. You should also tell your doctor if you've ever worked with metal or in the metal industry as very tiny fragments of metal can sometimes lodge in the body. If you do have any metal in your body it's likely that you won't be able to have an MRI scan. In this situation another type of scan can be used.

Before the scan, you'll be asked to remove any metal belongings including jewellery. Some people are given an injection of dye into a vein in the arm, which doesn't usually cause discomfort. This is called a contrast medium and can help the images from the scan to show up more clearly. During the test you'll lie very still on a couch inside a long cylinder (tube) for about 30 minutes. It's painless but can be slightly uncomfortable, and some people feel a bit claustrophobic. It's also noisy, but you'll be given earplugs or headphones. You can hear, and speak to, the person operating the scanner.

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 taken a few hours later. Areas of cancer are usually more active than surrounding tissue and show up on the scan.


Staging of GISTs

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 stage of your cancer helps your doctors decide on the most appropriate treatment.

Generally, sarcomas are divided into four stages:

  • Stage 1 – small and localised.
  • Stage 2 and 3 – spread into surrounding structures.
  • Stage 4 – spread to other parts of the body (this is known as secondary or metastatic cancer).

The stage of your cancer helps your doctors plan the best treatment for you. They also consider other factors including:

  • where the cancer started
  • how fast the cells are dividing
  • whether there are genetic changes (mutations) in the cells – your doctors will be able to tell you more about this.

If a cancer comes back after initial treatment, it is known as recurrent cancer. 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).


Treatment of GISTs

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 help your doctors decide on the best treatment for you.

Because GISTs are rare cancers, you should be referred to a specialist unit for treatment. You may have to travel to a hospital outside your area for this. 

The most common treatment for GIST is surgery to remove the tumour. Drugs known as growth inhibitors are used to treat GISTs that can't be removed with surgery.

Chemotherapy and radiotherapy don't work well for this type of cancer and so are not used.

Surgery

Surgery is usually the first choice of treatment for GIST. The surgeon removes the tumour along with some surrounding healthy tissue. If the tumour has begun to grow into other organs close by, these may also be removed. The aim is to make sure that all the GIST cells have been taken away. Surgery may also be used to treat GISTs that come back after treatment.

If the GIST is in your small bowel, you may have an operation to remove part of the small bowel. This doesn't usually have any long-lasting side effects.

If you have GIST in your stomach, you may need to have part or most of your stomach removed. This may mean making changes to your diet, particularly the size and frequency of your meals. Specialist dietitians can give you advice and support.

Your surgeon will tell you about any possible effects of the surgery. These will depend on the size of the tumour and where it is in your body.

Growth inhibitors

Growth inhibitors are drug treatments that are taken as tablets. They work by blocking signals in the cancer cells that make them grow and divide.

In about 85% of people with GIST, the tumour cells have a change (mutation) in a protein called KIT. This change means the GIST cells constantly get signals telling them to grow and multiply.

Treatment with growth inhibitors can block these signals. This may make the cancer shrink or stop it from growing. Growth inhibitors may be used to treat GISTs that can't be completely removed with an operation. There are two that can be used to treat a GIST. These are imatinib (Glivec®) and sunitinib (Sutent®).

Imatinib

The National Institute for Health and Care Excellence (NICE) is an independent organisation that assesses which drugs and treatments are available on the NHS in England and Wales. It recommends that imatinib is used as the first treatment for people with a GIST that can't be completely removed with surgery or has begun to spread. You can have treatment with imatinib for as long as it is working.

Imatinib may sometimes be given to people who have had surgery to completely remove a GIST but who also have a high risk of the cancer coming back. Treatment that’s given to reduce the risk of cancer returning is called adjuvant therapy. This treatment has been approved by NICE.

Adjuvant therapy with imatinib has been approved for use in certain situations by The Scottish Medicines Consortium (SMC) in Scotland.

If you live in Northern Ireland, you can find out from your cancer specialist whether this treatment is available.

The side effects of imatinib are usually mild or moderate. Some of the common side effects include:

Sunitinib

Sunitinib may be used if imatinib doesn't work or if it stops working. NICE has recommended sunitinib as a treatment option for people with GIST.

Common side effects of sunitinib include:

These side effects can usually be well controlled with medicines. Always tell your doctor if they continue or are troublesome.

Regorafenib

A new growth factor drug called regorafenib has been licensed for use in the US and Europe. It may be used if imatinib and sunitinib are no longer working. However it may not be available on the NHS. You can ask your doctor for more information.

There are several things you can do if a treatment is not available.

Clinical trials

Your doctor may ask you to take part in a clinical trial. Cancer doctors use clinical trials to assess new treatments. 

If you decide to take part in a trial, your doctor will 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.


Follow-up after treatments for GISTs

You will have regular check-ups at the hospital. Your doctor will examine you and ask about any side effects or symptoms. You will also have blood tests. You may also have a CT scan from time to time.

Let your doctor know if you have any new symptoms between appointments.


Your feelings

Having investigations and treatment for cancer can be very stressful.

You may have many emotions including anxiety, anger and fear. These are all normal reactions and are part of the process many people go through in trying to come to terms with their condition.

Everyone has their own way of coping with difficult situations. Some people find it helpful to talk to family or friends or their doctor or nurse. Others prefer to seek help from people outside their situation. Some people prefer to keep their feelings to themselves. There is no right or wrong way to cope, but help is there if you need it. Our cancer support specialists can give you information about counselling in your area.