Gastrointestinal stromal tumours – FAQ
GIST Support International share the most frequently asked questions regarding gastrointestinal stromal tumours (GISTs).
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What is GIST?
GISTs are rare cancers affecting the digestive tract or nearby structures within the abdomen. A GIST is a sarcoma (cancer that grows from cells of the body’s connective or supportive tissues such as bone, cartilage, tendons, nerves, fat, muscle, tissue around joints, or blood vessels).
Where do GISTS occur?
The most frequent site is the stomach (about 55%), followed by the duodenum and small intestine (about 30%), oesophagus (about 5%), rectum (about 5%), colon (about 2%), and other rare locations.
Because GIST cancers arise from the GI tract wall, they are usually attached to the outside of the involved organ (stomach or bowel), growing outward. Occasionally GISTs may grow inward through the muscle layer of the GI tract wall and then develop partly inside the digestive tract lumen.
Why are GISTS rare cancers?
GISTs are quite rare. Most cancers are carcinomas, meaning that they derive from cells in the skin, either outer-body skin or the skin-like lining of the internal body cavities and the digestive or gastrointestinal (GI) tract.
Most GI tract cancers are carcinomas, such as those commonly known as stomach and colon cancer. GISTs aren’t related to these common GI cancers; they are sarcomas. Of all adult cancers, sarcomas represent about 1%; GIST is one of the more common of about 50 types.
What causes GIST?
There are no known environmental or behavioural risk factors. Patients shouldn’t worry that their diet or lifestyle choices contributed to GIST. Random genetic mutations are the apparent cause. The majority show identified mutations in cell-surface proteins called tyrosine kinase receptors. Most GISTs show mutations in a gene that produces a growth factor receptor called KIT. A few GISTs show mutations in the gene for a closely related receptor for platelet-derived growth factor receptor alpha (PDGFR a or PDGFRA). A few GISTs are normal or wildtype for both these genes, and the causal mutations haven’t been identified. Almost all GISTs are sporadic, meaning that the mutations are random occurrences affecting a single individual. However, there are rare examples running in families due to an inheritable germline mutation. In addition, people affected by neurofibromatosis type 1 have an increased chance of developing GIST.
What are the symptoms?
Many patients (mostly those with smaller tumours) have no symptoms. Therefore, many GISTs are found incidentally through medical imaging or surgery for other purposes.
Larger tumours may cause symptoms that are generally related to the increased mass being accommodated in the abdominal cavity. These include digestive discomfort, sensations of abdominal fullness, or abdominal pain. Sometimes larger tumours may be detectable as a mass when feeling the abdomen, or as a visible enlargement of the abdomen. Some patients experience vomiting or diarrhoea. Bowel obstruction may occur. Sometimes a GIST perforates the stomach or gut lining and bleeds into the GI tract, resulting in black or tarry stools, or occasionally in vomiting of blood. Anaemia may result from chronic bleeding, leading to fatigue. Sometimes anaemia may cause tachycardia (heart to race). Weight loss may be seen. Very rarely a GIST may rupture, making its presence known with a medical emergency. Though such symptoms are possible, most are rather indistinct and merely related to the additional mass that is present in the abdomen.
What do I do if I’m diagnosed with GIST?
Because of the rarity, your role as a patient is essential. Many GIST patients choose to travel to expert sarcoma centres for consultations or for regular care. You may be able to find good care locally, but if you choose this course you’ll need to take more responsibility to participate in treatment decisions based on the realisation that you’ve a rare disease.
If your case is complicated, or if you have existing inoperable or metastatic tumours,seeing an expert as soon as possible is prudent. If nothing else, you can establish care and have them available to consult with your local doctors. Treatments for GIST are relatively new, with the primary treatment being only about 20 years old. Other treatments are continually being developed and are on the cutting-edge of medicine.
This article is sponsored by Accord Healthcare in the interest of education, awareness and support. The content and opinions expressed are entirely the support group’s own work and not influenced by Accord in any way.
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