{"entity":{"id":"lynch-syndrome-testing-uk","kind":"term","name":"Lynch syndrome testing after bowel cancer, and what it means for the family","aka":["cascade testing","mismatch repair testing","MLH1 methylation","Lynch surveillance"],"tldr":"Every bowel cancer should be tested for mismatch repair loss, and where it is found, for whether that loss is inherited. A Lynch syndrome result changes your treatment options, gives each of your children and siblings a one in two chance of carrying it, and puts you into regular colonoscopy; NICE also says to consider daily aspirin for more than two years.","summary":"Bowel Cancer UK says Lynch syndrome is a genetic condition that can raise the lifetime risk of bowel cancer to up to 80 percent and is estimated to cause around 3 percent of UK bowel cancer cases each year, many of them under 50; that between 175,000 and 200,000 people in the UK may have it and most do not know, because testing has not been systematic; and that testing should be offered at diagnosis of bowel cancer because the condition can affect treatment options. On families it says Lynch syndrome runs in families, so if a person has the condition there is a 50 percent chance that their children, brothers and sisters also have it, and family members of patients who test positive should be offered the same genetic tests, which it calls cascade testing. On surveillance it says people with Lynch syndrome should be placed in a screening or surveillance programme to receive regular colonoscopy every 18 months to two years, which can reduce the chance of dying from bowel cancer by as much as 72 percent, and that waits for these appointments are often unacceptably long. NICE NG151 (1.1.1) says to consider aspirin, to be taken daily and for a period of more than 2 years, to reduce the risk of colorectal cancer in people with Lynch syndrome, notes that in January 2020 this was an off-label use, and points to a NICE patient decision aid to support the discussion; the guideline also points to NICE's guidance on molecular testing strategies for Lynch syndrome in people with colorectal cancer. The order of the tests matters to a family: the tumour is tested for the mismatch repair proteins, and where MLH1 is lost the laboratory checks for MLH1 promoter methylation, which usually means the loss is sporadic rather than inherited, before a germline blood test is offered. The NHS page on genetic and genomic testing explains what happens to a sample and a result.","asOf":"2026-09-24","links":[{"label":"Bowel Cancer UK: Lynch syndrome","url":"https://www.bowelcanceruk.org.uk/campaigning/never-too-young/lynch-syndrome/"},{"label":"Bowel Cancer UK: family history","url":"https://www.bowelcanceruk.org.uk/about-bowel-cancer/risk-factors/family-history/"},{"label":"NICE NG151: colorectal cancer, recommendations","url":"https://www.nice.org.uk/guidance/ng151/chapter/Recommendations"},{"label":"NHS: genetic and genomic testing","url":"https://www.nhs.uk/tests-and-treatments/genetic-and-genomic-testing/"},{"label":"Macmillan: tests on the bowel cancer cells","url":"https://www.macmillan.org.uk/cancer-information-and-support/bowel-cancer/tests-on-the-bowel-cancer-cells"}],"tags":["gi","colorectal"],"related":[],"cancers":["colorectal"],"sections":[],"technologies":["germline-testing","msi-mmr-testing"],"targets":[],"drugs":[],"companies":[],"institutions":[],"pathways":[],"terms":["lynch-syndrome","msi","mlh1-promoter-methylation","colonoscopy"],"trials":[],"people":[],"bottlenecks":[],"keyPapers":[],"journals":[],"dependsOn":[],"notes":[],"category":"Genomics & genetics"},"route":"/terms/lynch-syndrome-testing-uk/","neighbours":{"cancer":[{"id":"colorectal","kind":"cancer","name":"Colorectal cancer","route":"/cancers/colorectal/"}],"technology":[{"id":"germline-testing","kind":"technology","name":"Germline (hereditary) testing","route":"/technologies/germline-testing/"},{"id":"msi-mmr-testing","kind":"technology","name":"MSI and mismatch-repair testing","route":"/technologies/msi-mmr-testing/"}],"term":[{"id":"colonoscopy","kind":"term","name":"Colonoscopy","route":"/terms/colonoscopy/"},{"id":"lynch-syndrome","kind":"term","name":"Lynch syndrome","route":"/terms/lynch-syndrome/"},{"id":"msi","kind":"term","name":"Microsatellite instability (MSI-H) / mismatch repair deficiency (dMMR)","route":"/terms/msi/"},{"id":"mlh1-promoter-methylation","kind":"term","name":"MLH1 promoter methylation (sporadic versus Lynch mismatch repair loss)","route":"/terms/mlh1-promoter-methylation/"}]}}