Testing for Lynch syndrome – what you need to know
Monday 9 April 2018
If any of your family members have bowel cancer, you might be worried about your risk of getting the disease. But bowel cancer is common and most people with a family history won’t need any tests or investigations. If you are worried about your family history or think you might have Lynch syndrome, we’ve addressed some of the common questions below..
What is Lynch syndrome?
Lynch syndrome is an inherited condition which puts people at a much higher risk of developing bowel cancer, as well as increasing the risk of other cancers including ovarian, stomach and womb cancer. Research shows that there could be over 200,000 people with Lynch syndrome but 95% don’t know they have it.
How can I find out if I have Lynch syndrome?
If you are diagnosed with bowel cancer you should be tested for Lynch syndrome at diagnosis – something we’ve blogged about before. If you’re worried that your family may have Lynch syndrome, tell your doctor if:
- Three or more of your family members in more than two generations have bowel cancer or a Lynch syndrome-related cancer, and
- At least one of these family members was aged under 50 when they were diagnosed, and
- One of these family members is a first degree relative of the other two.
What does being tested involve?
For people who have been diagnosed with bowel cancer, testing for the condition usually involves a three-stage process:
- Provisional molecular screening test. If Lynch syndrome is suspected a simple screening test (also known as a molecular test) can be carried out on the patient’s tumour tissue to identify if they are likely to have Lynch syndrome. This test looks for changes in the mismatch repair proteins.
- Genetic counselling. Consent is needed before genetic testing can take place. Before consent can be given a person suspected of having Lynch syndrome is required to see a genetic counsellor who will talk through the process and offer information, advice and support.
- Genetic testing. If changes to the genes are detected by the provisional screening test, the individual will be referred for full genetic testing to have their diagnosis confirmed. This involves a simple blood test and confirms that a change in the gene is present. Usually this takes around 6-8 weeks.
I’ve already been diagnosed with bowel cancer, but wasn’t tested for Lynch syndrome. Can I be tested now?
If you have any concerns about Lynch syndrome following a previous diagnosis of bowel cancer, you should speak to your GP who can refer you to a genetics team. Bring as much information about your family history, including who in your family has had bowel cancer and/or other types of cancer. This will provide your GP with a strong case of support to refer you to a geneticist.
Can my family members be tested for Lynch syndrome?
If you have Lynch syndrome, your family members may choose to have genetic testing. There is a one in two (50 per cent) chance of your children, brothers and sisters having Lynch syndrome.
If any of your family members have Lynch syndrome, they will be offered regular colonoscopies from the age of 25. This allows any growths (polyps) to be removed and cancer to be picked up early. Doctors do not usually start screening family members under this age because the risks of the colonoscopy are greater than the chance of picking up a cancer. You might be offered other preventative measures, such as taking aspirin, making lifestyle changes or having surgery to remove part of the colon (colectomy). Ask your healthcare team for more information.
Can I get a private test for Lynch syndrome? How much will it cost?
If you have a family history of bowel cancer or have concerns about Lynch syndrome, you should speak to your GP.
We can’t recommend any over the counter tests as these will vary in quality, reliability and price. We would always advise you use caution if you decide to take this approach, as the results could be misleading. It’s also important to make sure that genetic counselling is available as part of the service, this gives you the opportunity to discuss your situation and any concerns in more detail.
If you do want to pay for private review, a geneticist or genetic counsellor should be able to refer you. Some private companies can be contacted directly.