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Gastro-Intestinal Stromal Tumours

Overview

Gastrointestinal Stromal Tumours (GIST) are rare tumours that develop in the wall of the digestive tract. Unlike traditional cancers of the stomach or intestines, GISTs arise from the muscle layer of the gastrointestinal tract lining. They behave differently from most other gastrointestinal cancers. The most common site for GIST is the stomach, although they have been reported in the food pipe (oesophagus), small intestine, and even the large intestine.

GISTs may not always cause obvious symptoms at first and are sometimes found by chance during tests for other problems. When symptoms do appear, they can include:

  • Bleeding: presents as blood in vomit or passing dark stools (called melena). Sometimes, the only sign is anaemia (low haemoglobin) detected on a routine blood test.
  • Abdominal pain or discomfort and nausea

  • Loss of appetite and unexplained weight loss

    Incidental (by chance) finding on an ultrasound or CT scan performed for any other reason

Most GISTs develop due to genetic changes (mutations) in a growth-related gene called KIT, or sometimes, PDGFRA. These mutations cause an uncontrolled growth of the cells in the digestive tract wall.  Age has also been reported as a risk factor for these tumours, given that they commonly occur in adults between 40 and 70 years of age.

  • GISTs are usually not inherited (do not commonly run in families).
  • The exact trigger for these genetic changes is not always known.

Doctors may use a combination of tests to confirm a diagnosis of GIST:

  • Endoscopy: a thin flexible tube with a camera is used to see the tumour and take a small sample (biopsy). Depending on the location, the endoscopy may be an upper GI endoscopy (for stomach/oesophagus) or a colonoscopy (for large intestine).
  • CT scan: provides detailed images of the lesion (tumour), its size, extent, and the relationship of the tumour to the surrounding structures. It also helps doctors plan the surgery.
  • Histopathology and immunohistochemistry (IHC): after biopsy or surgery, the tissue sample is studied under a microscope. Tests for specific proteins such as CD117 (KIT) confirm the diagnosis.

The main treatment for GIST depends on the size, location, and risk category of the tumour:

  • Surgery: The first and most important treatment is surgical removal of the tumour with a margin of normal tissue. The removed specimen is tested to assess risk of recurrence.
  • Targeted Therapy (Imatinib/Gleevec):
    • A type of oral chemotherapy that specifically blocks abnormal growth signals in GIST cells (called a tyrosine kinase inhibitor). The medication works best in individuals who express the antibody CD117 (Tyrosine Kinase Inhibitor positive: c-KIT positive).
    • Used before surgery (neoadjuvant therapy) to shrink large tumours and make surgery possible.
    • Used after surgery (adjuvant therapy) if there is a high risk of recurrence (based on size, mitotic rate, or spread).
  • Monitoring: Regular scans and follow-ups are required since some GISTs may recur even after treatment.

You should consult a doctor if you notice:

  • Unexplained abdominal pain or discomfort
  • Blood in vomit or stools (red or black in colour)
  • Unexplained weight loss or loss of appetite
  • Persistent anaemia (low haemoglobin) despite treatment
  • Sudden severe abdominal pain with vomiting or swelling (may suggest bleeding or rupture of a tumour – a medical emergency)

Patients with suspected or confirmed GIST should consult:

  • Gastroenterologist for initial diagnosis through endoscopy.
  • Surgical oncologist or GI cancer surgeon for surgery and treatment planning.
  • Medical oncologist for targeted therapy (Imatinib) and long-term follow-up.

Disclaimer:

The information in this Health Library is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare professional with any questions about a medical condition or before starting any treatment. Use of this site and its content does not establish a doctor–patient relationship. In case of a medical emergency, call your local emergency number or visit the nearest emergency facility immediately.