Gastrointestinal Stromal Tumour (GIST)

Most GISTs are caused by a change (mutation) in a gene, commonly KIT or PDGFRA, that makes cells grow without control. This change usually happens by chance during life and is not inherited. Rarely, GIST runs in families or is linked to certain inherited syndromes. There is no known lifestyle cause. Knowing the mutation matters because it helps choose the best medicine.

GIST is rare. It is mostly diagnosed in middle-aged and older adults and is uncommon in children. Small ones are often found by chance during a scan or endoscopy for another reason.

GIST is usually suspected on endoscopy (a camera test) as a smooth bulge under the lining, or on a CT or MRI scan. Endoscopic ultrasound (a camera with an ultrasound probe) can show which layer it comes from and allow a needle biopsy (a small tissue sample). Pathologists examine the tissue for GIST markers such as KIT and count the dividing cells. Genetic testing of the tumour is done in many cases. Staging scans look for spread, most often to the liver or the lining of the belly.

A GIST diagnosis is worrying, but you can play an active part in your care.

• Ask for your care to be reviewed by a multidisciplinary team including a surgeon and an oncologist.

• Keep every follow-up scan and clinic appointment.

• Take tablets exactly as prescribed and report side effects early instead of stopping on your own.

• Stay as active as you can; gentle exercise helps energy and mood.

• Seek emotional support from family, friends or a counsellor.

No diet treats GIST, but good nutrition helps you cope with surgery and treatment.

• Eat balanced meals with enough protein to keep strength and weight.

• Small frequent meals can help if you feel full quickly or have nausea.

• Some tablets can interact with grapefruit, pomelo and some herbal products; ask your pharmacist before consuming them.

• Ask a dietitian for help if you lose weight or after a stomach operation.

Targeted tablets are a key treatment for many people with GIST. Your oncologist selects the medicine based on your tumour's genetic profile and monitors you closely.

• Imatinib is the standard first targeted tablet for many GISTs; other medicines are used if the tumour stops responding or has a different genetic type.

• These medicines may be given before surgery to shrink a large tumour, or after surgery to lower the chance of return, depending on risk.

• Common side effects include tiredness, swelling around the eyes or legs, nausea, diarrhea and skin changes; your team can help manage them.

• Check with your doctor before starting any other medicine, supplement or herbal product.

Never stop these tablets or change the amount on your own.

Surgery is the main curative treatment when the tumour can be removed completely.

• Surgery removes the tumour with a margin of healthy tissue, often keeping as much of the organ as possible.

• Many operations are done by keyhole (laparoscopic) surgery when suitable.

• Some very small tumours are watched with regular endoscopy or scans, if your team considers this safe.

• Tumours that have spread may be treated mainly with tablets, and sometimes with other local treatments for the liver.

The discovery of tumour gene changes led to targeted tablets (called tyrosine kinase inhibitors) that block the signals driving the tumour, which has changed outcomes for many people. Different genetic types respond differently, and newer medicines are available for tumours that stop responding. Care in a centre experienced with sarcomas is recommended.

The outlook varies widely and depends on the tumour size, where it is, how fast its cells divide, whether it has spread and whether it can be removed completely. Many small, low-risk tumours are cured by surgery, and targeted tablets can control larger or spread tumours for long periods. Long follow-up is needed because GIST can return. Your team can explain the risk level of your own tumour.

• How big and how risky is my tumour?

• Has my tumour had genetic testing, and what does it mean?

• Do I need surgery, tablets, or both, and for how long?

• What side effects should I watch for?

• How often will I need scans and follow-up?

This guide comes from the Saudi Gastroenterology Association (SGA) patient library, prepared by the Approved for publication by SGA; individual clinician review is ongoing. Last reviewed: 2026-04-24. It is for education and does not replace your doctor's advice.