Testing for an inherited genetic predisposition to bowel cancer
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What is bowel cancer genetic testing?
1 in 15 men and 1 in 18 women will develop bowel cancer at some point during their lifetime. Over 42,000 people are diagnosed with bowel cancer each year, making it the fourth most common cancer in the UK after breast, lung and prostate cancers1.
Most bowel cancers occur by chance, and less than 20% are familial. In families where bowel cancer is hereditary, it may be possible to find the genetic change (variant) which is responsible for the cancers. This allows appropriate bowel cancer tests and risk-reducing options to be offered to the family.
Genetic testing can be carried out to identify if a person has an inherited genetic predisposition to developing bowel cancer. This involves reading through specific genes and looking for spelling mistakes or ‘variants’ that stop the gene from working.
What are the red flags to be aware of?
Individuals with hereditary bowel cancer generally show one or more of the following:
- Bowel cancer diagnosed at a young age (before the age of 50)
- Bowel cancer that has screened positive for Lynch syndrome (abnormal IHC/ MSI)
- Several relatives with bowel cancer
- Relatives with bowel cancer and/or related cancers (such as womb or ovarian cancer)
- Multiple bowel polyps* in an individual
- Multiple generations of cancer
*Cancer usually starts as a benign growth known as a polyp. Not all polyps will become cancerous, and they can often be removed during screening.
Which genes are associated with an increased risk of developing bowel cancer?
Our Bowel Cancer Genetic Counselling and Testing service is a genetic test for individuals with bowel cancer or a strong family history of bowel cancer. It examines the DNA code of eleven genes known to be associated with an increased risk of developing bowel cancer. BowelGene looks for variants in the following genes: APC, MUTYH, PTEN, SMAD4, BMPR1A, STK11 and the Lynch Syndrome genes MLH1, MSH2, MSH6, PMS2 and EPCAM.
If I have a bowel gene variant, what can be done about it?
If a pathogenic variant is identified in one of the genes tested, this means that you have an increased risk of developing bowel cancer and possibly other cancers. Your exact risks will depend on which gene the variant has been found in. Extra screening and/or risk-reducing strategies will be discussed. If a genetic variant is identified, it will then be possible to offer predictive testing to other people in your family, to see if they also have the same variant.
Learn more about genetic counselling here. For more information on testing for bowel cancer, please click here.
References
Professor Andrew Beggs
Clinical Advisor for Bowel Cancer & Genetics
Professor Andrew Beggs is a Professor of Cancer Genetics & Surgery at the University of Birmingham and University Hospitals Birmingham NHS Foundation Trust. He runs a diverse research group of scientists and clinicians studying the molecular determinants of response to cancer treatments using organoid models and next-generation sequencing models. He is also an active cancer clinician, running a familial cancer clinic for the West Midlands Region and one of the national gastrointestinal polyposis centres. Professor Beggs acts as a scientific adviser to the UK Department of Health and Social Care and Genomics England.
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