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Health condition · Clinically reviewed

Lynch syndrome, the inherited cancer risk you can actually manage.

A faulty mismatch repair gene raises the risk of bowel and womb cancer well above average - but structured surveillance and cascade testing change the outlook for whole families.

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Why trust this guide

  • 01

    Clinically reviewed

    Written by our editorial team and reviewed by a registered UK clinician before publication.

  • 02

    Sourced from guidance

    Checked against NICE DG27, the British Society of Gastroenterology and peer-reviewed sources you can see at the end.

  • 03

    Current for 2026

    Reflects universal tumour testing, surveillance colonoscopy intervals and immunotherapy for MSI-high cancers.

Key facts

Lynch syndrome at a glance.

The essentials, in plain English - what it is, which genes are involved, and how it's managed in the UK today.

  • What it is

    An inherited fault in one of the mismatch repair genes - the most common cause of hereditary colorectal cancer.

  • Genes involved

    MLH1, MSH2, MSH6, PMS2 or EPCAM - each carries a different risk profile and surveillance schedule.

  • Inheritance

    Autosomal dominant - each child of a carrier has a 50% chance of inheriting the altered gene.

  • Main cancer risks

    Colorectal cancer up to 80% lifetime risk; endometrial cancer up to 60% in women, plus ovarian, gastric and other sites.

  • How it is found

    Universal mismatch repair testing on new bowel and womb cancers, family history criteria, or direct genetic testing.

  • Why it matters

    Regular surveillance and, where appropriate, risk-reducing surgery substantially cut cancer deaths in carriers.

Why this guide matters

A family diagnosis, not just a personal one.

Lynch syndrome is often discovered through a tumour test rather than symptoms - and the diagnosis reaches far beyond the person first tested.

  • Universal testing finds it early

    Every new bowel and womb cancer in the UK is now screened for mismatch repair deficiency - many people learn they carry Lynch syndrome this way.

  • Surveillance genuinely saves lives

    Regular colonoscopy and gynaecological review catch cancers early or prevent them outright - the single biggest lever a carrier has.

  • One result changes the whole family

    A confirmed mutation opens the door to cascade testing for parents, siblings and children, each with a 50% chance of carrying it too.

How the diagnosis is made

From a tumour test to a family plan.

The steps a UK MDT will normally follow, in order - so you know what to expect and why it matters for your relatives too.

  1. 01

    Screening

    Universal tumour testing

    NICE mandates that every new colorectal and endometrial cancer is tested for mismatch repair deficiency using immunohistochemistry and MSI testing.

  2. 02

    Screening

    Family history review

    Amsterdam and Bethesda criteria flag families with multiple relatives affected by Lynch-related cancers, often at a young age.

  3. 03

    Screening

    MLH1 methylation and BRAF check

    In MLH1-deficient tumours, methylation and BRAF testing rule out a sporadic cause before germline testing is offered.

  4. 04

    Confirming

    Referral to clinical genetics

    A positive tumour screen or strong family history triggers referral for pre-test counselling and germline analysis.

  5. 05

    Confirming

    Germline genetic testing

    Blood or saliva testing confirms a mutation in MLH1, MSH2, MSH6, PMS2 or EPCAM - see our hereditary cancer panel guide.

  6. 06

    Extending

    Cascade testing for relatives

    Once a family mutation is identified, first-degree relatives are offered predictive testing so risk can be managed early.

  7. 07

    Extending

    MDT surveillance planning

    A specialist multidisciplinary team - genetics, gastroenterology and gynaecology - agrees a personalised surveillance and prevention plan.

Typical timeline: tumour screen to confirmed result in a matter of weeks.

Presentation

How Lynch syndrome actually comes to light.

Unlike most conditions in this series, Lynch syndrome rarely announces itself with symptoms - it's usually identified through testing and family history.

  • Strong family history

    Multiple relatives with bowel, womb or related cancers, often across two or more generations.

  • Young-onset cancer

    Colorectal or endometrial cancer diagnosed before age 50 is a classic trigger for Lynch syndrome testing.

  • Multiple primary cancers

    A personal history of more than one Lynch-related cancer, sometimes years apart.

  • Endometrial cancer first

    In women, endometrial cancer often precedes colorectal cancer and can be the first clue to the diagnosis.

  • MSI-high tumour biology

    Tumours show microsatellite instability - a distinct molecular signature identified on routine pathology testing.

  • Skin and sebaceous lesions

    Sebaceous adenomas or carcinomas can signal the Muir-Torre variant of Lynch syndrome.

  • Often no symptoms at all

    Most carriers are identified through testing or family history, not through symptoms - this is a genetic risk, not an illness in itself.

  • Red flag - Amsterdam criteria met

    Three or more relatives, two generations, one under 50 - meeting these criteria warrants urgent genetics referral.

Management

How Lynch syndrome is managed in the UK.

Structured surveillance first, chemoprevention and selective surgery alongside it - and immunotherapy that has transformed outcomes when cancer does develop.

  • Colonoscopy surveillance

    From around age 25, every 1 to 2 years depending on the gene involved - the cornerstone of reducing colorectal cancer deaths in Lynch syndrome.

  • Gynaecological surveillance

    Regular review for women, with risk-reducing hysterectomy and bilateral salpingo-oophorectomy considered once childbearing is complete.

  • Aspirin chemoprevention

    Daily aspirin, informed by the CAPP2 trial, reduces colorectal cancer incidence in confirmed carriers over the long term.

  • Selective gastric surveillance

    Upper endoscopy is offered to those with a family history of gastric cancer or higher-risk gene variants such as MLH1 and MSH2.

  • Risk-reducing surgery

    Considered on an individual basis for very high-risk carriers or those who cannot maintain surveillance, balanced against quality of life.

  • Immunotherapy for MSI-high cancer

    Checkpoint inhibitor immunotherapy is highly effective in MSI-high Lynch-related cancers - see our immunotherapy checkpoint clinic guide.

  • Cascade genetic counselling

    Structured counselling helps relatives understand their own testing options and what a positive or negative result means for them.

  • MDT specialist care

    Ongoing input from clinical genetics, gastroenterology and gynae-oncology, often alongside charities such as Bowel Cancer UK.

What this guide is based on

The sources behind every claim on this page.

UK national guidance and specialist society standards, current at the time of last review.

Key references

Guidelines and standards we relied on.

A quiet reminder

This guide is for information, not medical advice.

Your clinical genetics team knows your family history and can tell you which parts apply to you. If in doubt, get seen.

  • NICE. Molecular testing strategies for Lynch syndrome in people with colorectal cancer (DG27).

  • British Society of Gastroenterology (BSG). Guidelines on genetic testing and management of Lynch syndrome.

  • CAPP2 trial. Long-term effect of aspirin on cancer risk in carriers of hereditary colorectal cancer.

  • Bowel Cancer UK. Information and support for people with Lynch syndrome.

Red flags

When to seek attention between surveillance visits.

Surveillance catches most problems early, but new symptoms in between appointments should never simply wait for the next scheduled check.

  • Rectal bleeding or bowel habit change

    New, persistent bleeding or a change in bowel habit in a known carrier needs prompt assessment, not just routine surveillance.

  • Postmenopausal bleeding

    Any bleeding after menopause in a Lynch carrier should be investigated urgently for endometrial cancer.

  • Unexplained weight loss or anaemia

    Both can signal an interval cancer developing between surveillance visits and deserve prompt investigation.

  • Missed or overdue surveillance

    Falling behind on colonoscopy or gynaecological surveillance meaningfully raises risk - re-engage with your specialist team promptly.

  • New abdominal or urinary symptoms

    Lynch syndrome also raises the risk of gastric, urinary tract and small bowel cancers - new symptoms in these areas warrant review.

  • Family history not yet assessed

    If several relatives have had bowel or womb cancer and no one has discussed genetics, ask your GP for a referral.

  • Considering pregnancy

    Carriers planning a family may wish to discuss reproductive options, including pre-implantation genetic testing, before conceiving.

Living with it

A manageable risk, not a diagnosis of illness.

Four things that make the biggest difference over a lifetime - keeping surveillance on schedule, telling your family, planning ahead, and using the support around you.

A quiet reminder

Carrying a mutation is not the same as having cancer.

It is a reason for closer monitoring, not a verdict - and that monitoring is precisely what keeps most carriers well.

  1. 01 Attend

    Keep every surveillance appointment

    Colonoscopy and gynaecological checks work best when kept on schedule - gaps are when interval cancers appear.

  2. 02 Share

    Tell your relatives

    A confirmed mutation matters to your children, siblings and wider family - cascade testing only works if the news reaches them.

  3. 03 Discuss

    Talk through family planning early

    Options exist for reducing the chance of passing on the mutation - raise this with genetics well before you plan to conceive.

  4. 04 Support

    Use the support that exists

    Charities such as Bowel Cancer UK and Lynch syndrome-specific groups offer practical and emotional support alongside your clinical team.

Frequently asked

Everything we get asked about Lynch syndrome.

Quick answers on genetics, cancer risk, surveillance and testing your family.

  • What is Lynch syndrome?

    An inherited condition caused by a fault in one of the mismatch repair genes - MLH1, MSH2, MSH6, PMS2 or EPCAM. It is the most common cause of hereditary colorectal cancer and substantially raises the lifetime risk of several other cancers, particularly endometrial cancer in women.

  • How is Lynch syndrome diagnosed?

    Most people are identified through universal testing of a new bowel or womb cancer for mismatch repair deficiency, or through a strong family history meeting the Amsterdam criteria. A positive screen is confirmed with germline genetic testing of blood or saliva.

  • What cancer risks does Lynch syndrome carry?

    Colorectal cancer risk can reach up to 80% over a lifetime, and endometrial cancer risk up to 60% in women. There is also an increased risk of ovarian, gastric, urinary tract, small bowel, pancreatic, brain and skin cancers, though the exact level of risk depends on which gene is affected.

  • How often will I need a colonoscopy?

    Surveillance typically starts around age 25 and is repeated every 1 to 2 years, with the exact interval and starting age depending on which mismatch repair gene is involved. Your gastroenterology team will set a personalised schedule.

  • Does aspirin really reduce cancer risk?

    Evidence from the CAPP2 trial shows that daily aspirin taken over several years reduces colorectal cancer incidence in confirmed Lynch syndrome carriers. Whether it is right for you depends on your individual risk factors, and it should be discussed with your specialist team.

  • Should my children be tested?

    Each child of a carrier has a 50% chance of inheriting the altered gene, so cascade genetic counselling and testing are usually offered once a family mutation is confirmed. Testing decisions for children are made carefully and usually deferred until an appropriate age with full genetic counselling.

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