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?
BowelGene 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, MHS2, 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.
Find out more about genetic counselling here, and for more information on testing for BowelGene, please click here.
References
- https://www.cancerresearchuk.org/health-professional/cancer-statistics/statistics-by-cancer-type/bowel-cancer
Sarah Beck | Registered Genetic Counsellor
Sarah Beck is a Registered Genetic Counsellor who has worked within the field of cancer genetics since 2001, working for GeneHealth at Check4Cancer since 2014.
Sarah graduated from the University of Newcastle upon Tyne with a BSc (Hons) in Genetics in 2000 and in 2003, was awarded an MSc in Genetic Counselling from Manchester University. Sarah gained AGNC (Association of Genetic Nurses and Counsellors) professional registration in 2006 and HGSA (Human Genetics Society of Australasia) registration in 2009 whilst working as a Genetic Counsellor in Auckland, New Zealand for three years.
Sarah has previously worked for the NHS Clinical Genetics Services in Oxford, Cambridge and Southampton and she also worked on the CAPP2 Lynch Syndrome cancer prevention study in Newcastle. Sarah is a GCRB sign-off mentor and assessor for new Genetic Counsellors seeking GCRB registration.
