Gastro-intestinal Stromal Tumour (GIST)
Gastro-intestinal stromal tumour (GIST) is a rare type of cancer found in the gastro-intestinal tract, which is part of the body’s digestive system. GISTs are believed to begin in cells found between muscle layers of the gastro-intestinal tract, called Interstitial cells of Cajal (ICC). GIST growth usually begins in the connective tissue in the wall of the affected organ and grows outwards.
The common location of GISTs are in the stomach (50 to 60%) and small intestines (30 to 40%) but can occur in any site in the digestive system. Other possible GIST sites are the oesophagus, rectum, and colon. GISTs found outside of the gastro-intestinal tract, such as in the liver, pancreas, lining of gastro-intestinal tract (omentum, mesentry or peritoneum) and gallbladder are extremely rare. They are known as extra gastrointestinal stromal tumours.
GISTs can either be benign, meaning it is not cancerous, or malignant. Malignant cancer cells are harmful because they have greater uncontrollable growth and can spread throughout the body.
Early stages of gastro-intestinal stromal tumour often do not cause any symptoms or only show in the form of non-specific symptoms, which can be commonly found in other illnesses. Most GIST diagnoses occur during more advanced stages of the disease and symptoms can vary widely among individuals.
GIST symptoms may include:
- Pain in the abdomen
- Mass in the abdomen
- Feeling of bloating
- Difficulty or pain swallowing
- Unexplainable fatigue
- Vomit or stools containing blood (either bright red or very dark)
- Anaemia (low red blood cell count)
If you experience any of these symptoms or have concerns, please contact your general practitioner (GP).
GIST cases are rare and estimated to cause between 0.1% and 3% of GI cancer in Australia. The risk of GIST diagnosis increases with age, with GIST incidence peaking among people in their fifties and sixties.
Like many other cancers, increased age can contribute to a greater chance of developing GIST, but there are currently no specific known environmental or behavioural factors found to increase the risk. However, certain inherited genetic syndromes have been linked to increased risk of developing GIST. This includes Neurofibromatosis type 1, an inherited genetic condition in which tumours grow in the nervous system and Carney Triad (a rare syndrome defined by the coexistence of three specific tumours and typically affecting young people).
The type of clinical tests will vary depending on the individual’s symptoms.
The medical practitioner will usually begin testing with a physical exam to check for swelling or lumps in the abdomen. Imaging scans will also be used to see if the tumour is present. This includes x-ray, computed tomography (CT) scans and/ or magnetic resonance imaging (MRI) or a positron emission tomography (PET) scan to examine the stomach and surrounding organs in more detail.
An upper gastro-intestinal tract endoscopy may be required to visualise any tumours in the stomach. This involves passage of a tube with a camera at one end through the mouth. Sometimes special techniques, such as endoscopic ultrasonography (EUS), may be required for better visualisation of the tumour to differentiate it from other lesions.
If a GIST is found, a biopsy or small body tissue sample will be taken to examine under a microscope to see if there are any cancer cells. This will help determine whether the GIST is malignant or benign.
Surgery is the most common type of treatment for GISTs, however, this depends on the location and whether the tumour presents at an advanced stage. In many cases GISTs are extremely small. If the tumour is small and in a single location, complete surgical removal of the tumour and the surrounding tissue is possible.
If surgical removal is not possible the doctor may recommend biological therapies. Imatinib is used to treat GIST that cannot be removed by surgery. Imatnib is taken in tablet form and works by blocking a chemical involved in cancer growth, which may slow down the growth of a tumour.
Currently there is no standard screening test for GIST in Australia.
As the current known risk factors of GIST are genetic syndromes and age, there are no known protection methods to reduce the likelihood of developing GIST.
Changing outcomes for people with gastro-intestinal cancer since 1991