Gastrointestinal Stromal Tumour

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A gastrointestinal stromal tumour (GIST) is a rare tumour of the digestive tract wall, usually driven by a KIT or PDGFRA gene mutation and treated with targeted therapy.

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Key facts

  • A gastrointestinal stromal tumour (GIST) is a rare soft-tissue tumour that grows in the wall of the digestive tract, most often the stomach or small intestine.
  • Most GISTs carry a mutation in the KIT or PDGFRA gene, which is what makes them respond to targeted drugs rather than standard chemotherapy.
  • Surgery is the primary treatment for tumours that can be removed; imatinib is the established first-line drug for higher-risk, advanced, or recurrent disease.
  • See a doctor promptly for unexplained abdominal bleeding, a growing abdominal mass, or unexplained anaemia.

What a GIST is

A GIST develops from the interstitial cells of Cajal, specialized cells in the digestive tract wall that help regulate gut movement. It differs from more common digestive cancers like stomach or bowel cancer, both in how it behaves and in how it's treated. Small GISTs often cause no symptoms and are found incidentally during imaging or endoscopy done for another reason. Larger tumours can cause abdominal discomfort, a palpable mass, bleeding, or anaemia from chronic blood loss.

Diagnosis

Diagnosis relies on imaging, usually CT or MRI, followed by a biopsy checked with immunohistochemistry for the KIT (CD117) protein marker that most GISTs express. Confirming KIT or PDGFRA mutation status also guides which targeted drug is likely to work.

Treatment

Surgery to remove the tumour is standard for GISTs that are localized and operable. Targeted therapy is the mainstay once drug treatment is needed: imatinib, a tyrosine kinase inhibitor, is the established first-line option. It's used after surgery to lower the chance of recurrence in higher-risk tumours, and as ongoing treatment for advanced or metastatic disease that can't be fully removed. Because most GISTs carry a KIT or PDGFRA mutation, they respond well to this molecular approach even when conventional chemotherapy would not help.

Follow-up

Regular imaging continues after treatment, since GISTs can recur years after the original tumour was removed or controlled. Anyone with unexplained abdominal bleeding, a growing lump, or persistent unexplained anaemia should get a prompt medical evaluation.

This page is educational and does not replace advice from a doctor or pharmacist who knows your health history.