Gastrointestinal Stromal Tumour (GIST)

A gastrointestinal stromal tumour is a growth in the digestive tract that requires specialist testing to determine its behaviour and treatment.

Often shortened to GIST, it begins in specialised support cells in the wall of the digestive tract. It may arise in the stomach or intestine and can vary in size and behaviour. Laboratory testing of tumour tissue helps the specialist identify features that guide both surgery and medicine choices.

Some GISTs cause no symptoms and are found during tests for another reason. Blood in the stool and persistent abdominal pain are common presentations of GIST. Other possible changes include feeling full sooner than expected, nausea, fatigue from blood loss, or a noticeable abdominal swelling. Blood in stool needs prompt medical assessment, especially with weakness, dizziness or black stools.

GIST develops when cells in the digestive tract acquire changes that make them grow differently. These changes are usually examined in the tumour itself to help select treatment. Most people cannot identify a single event or lifestyle choice that caused their GIST, and it is not contagious.

A GIST may remain localised in the organ where it began, or it may grow into nearby structures or spread to other sites. The pathology report, tumour location and scan findings are considered together. This assessment helps the team decide whether to operate first, use targeted medicine first, or monitor a small tumour in a planned way.

Most GISTs occur without a known inherited cause. Rare inherited conditions can be relevant when there is a pattern of GIST or related tumours in close relatives. Tell the specialist about relatives with unusual tumours, as this may affect whether genetic counselling is considered. A family history alone does not diagnose GIST.

Assessment may start with blood tests and imaging such as a CT or MRI scan. An endoscopy may be used when the tumour is near the stomach or upper intestine. A biopsy obtains tissue for a pathologist, who can confirm GIST and arrange molecular testing. In some cases, the team may plan surgery before a biopsy when it is safer or more informative.

Tumour removal surgery is often considered for a localised GIST that can be removed safely. Targeted therapy may be used before surgery to shrink or control a tumour, after surgery in selected situations, or when disease cannot be removed. The medicine choice is informed by the tumour’s molecular result, so treatment plans are individual.

Write down changes in pain, appetite, bowel habits and energy so the clinical team can act on them early. Nutrition support can be helpful when eating becomes difficult. If taking targeted medicine, report new swelling, rash, diarrhoea, fatigue or other changes rather than adjusting the dose on your own.

A tumour can bleed into the digestive tract or narrow part of the bowel, depending on its site. Seek urgent care for vomiting blood, black or bloody stool, sudden severe abdominal pain, fainting, or inability to keep fluids down. Your team can also explain symptoms that may occur after surgery or while receiving medicine.

There is no established routine screening test for people without symptoms or a relevant inherited condition. You did not cause a GIST by a particular food, exercise habit or everyday activity. The practical focus is on assessing persistent digestive symptoms and keeping planned follow-up scans and appointments.

Care is commonly coordinated by a surgical oncologist and medical oncologist, with radiology, pathology and digestive specialists involved as needed. Ask whether your tumour has had molecular testing, what the treatment goal is, and which symptoms should prompt a same-day call. These questions make it easier to take part in decisions.