Gastrointestinal stromal tumour (GIST) is a type of sarcoma that develops in the gastrointestinal (GI) tract.
The GI tract is a long tube running through the body from the oesophagus (gullet) to the anus (back passage), and includes the stomach and intestines.
Every year, around 900 people in the UK are diagnosed with GIST. It most commonly affects people between the age of 55 and 65. GISTs are very rare in children and young people.
There are also a number of rarer subtypes of GIST:
Wild-type GIST: A type of GIST that is not caused by a KIT or PDGFRA cell mutation
Paediatric GIST: A GIST affecting children and young adults
Syndromic GIST: A type of GIST linked to Carney’s Triad Syndrome and Carney-Stratakis Syndrome and Neurofibromatosis
Familial GIST: A rare inherited form of GIST
Signs and symptoms
Symptoms of GIST can vary depending on the size and location of the tumour. They may include:
- Blood in your poo or vomit
- Anaemia (low level red blood cells)
- Fever and sweating at night
- Discomfort or pain in your stomach
- Painless lump in the stomach
- Feeling sick and vomiting
- Weight loss
A specialist doctor will diagnose GIST through a series of tests. These may include:
- Clinical examination – looking at or feeling any lump
- A scan – taking pictures of the inside of the body
- A biopsy – taking and testing a sample of tissue
A clear diagnosis will be made after a pathologist with experience in GIST has examined a tissue sample.
When your tumour is removed it should be sent for mutational analysis. This test finds out what mutation has caused the GIST.
There are two main sites of mutation in GIST:
• In a gene called KIT
• In a gene called PDGFRA
KIT is more common. However, if your GIST is caused by a PDGFRA mutation it may affect your treatment options. This is because the drugs used to treat GISTs may not work properly on GISTs caused by a PDGFRA mutation.
To read more about scans and tests, click here.
The type of treatment you receive depends on what part of the GI tract it is in and the risk category of your GIST coming back.
Surgery is usually the first treatment method used for GIST. The surgeon will remove the tumour and will aim to take out an area of normal tissue too; this is known as taking a margin. It allows cancer cells that are not visible to the naked eye to be removed along with the tumour. This can reduce the risk of the cancer coming back.
GIST in the small bowel
You may have an operation to remove part of the small bowel. This usually doesn’t have any long-lasting side effects.
GIST in your stomach
You may need to have part or most of your stomach removed. This will affect how you eat. Specialist dietitians can give you advice and support on making changes to your diet.
Oral anticancer targeted drugs
If your tumour is too large to be removed safely, or your GIST has already spread to other parts of the body, it can be treated using targeted drugs.
The three targeted drugs that are used for GIST are Imatinib, Sunitinib, and Regorafenib.
Imatinib is the first treatment choice for GIST patients. It is effective in 80% of patients and on average will control the disease for about two years. Sometimes the tumour develops a resistance to imatinib and hence over time it stops working. If this happens, sunitinib is used as a second treatment option.
Regorafenib (Stivarga) is used to treat people who have GIST that cannot be operated on or has spread to another part of the body. If you have had treatment with Imatinib and Sunitinib that has not worked or has caused bad side effects, then Regorafenib is an alternative treatment.
Treatment with these drugs may harm your fertility. Please speak to your doctor or clinical nurse specialist about your options for preserving fertility before treatment.
It is not advised to become pregnant, breastfeed or father a child when on these treatments.
Treatment before surgery
If the tumour was too large to be removed at the time of diagnosis, it may be treated by a targeted drug like imatinib. If enough shrinkage has occurred after 6–12 months, it may be possible to do an operation more safely.
Treatment after surgery
Some people who have had their tumour removed but are at a high risk of the cancer coming back may have a treatment called adjuvant therapy. Adjuvant therapy is an additional treatment after the first treatment which reduces the risk of the cancer returning.
Clinical trials suggest that if it is to be used, giving it for three years is likely to give the best results. Using imatinib as an adjuvant therapy has been approved for use in certain
circumstances in Scotland by The Scottish Medicines Consortium (SMC). Adjuvant imatinib is currently available in England and Wales via the Cancer Drugs Fund.
After your treatment is finished you will have follow-up appointments for several years. This is where your doctor can look for signs of your GIST coming back. At follow up appointment you will have:
• A chance to discuss symptoms
• An examination to look for any signs of GIST returning such as a CT or MRI scan
If your GIST does come back a new treatment plan will be put in place for you.
A recurrence of cancer may appear in other parts of the body. This is called a metastasis or secondary cancer.
Secondary cancers in GIST patients can appear anywhere, but are more common in the abdomen and liver. You will be treated with the targeted drugs imatinib and sunitinib. During treatment, you will be monitored to see how your cancer is responding to these drugs. You should get support from your sarcoma clinical nurse specialist on managing symptoms and side effects.