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At a glance:

  • Lynch syndrome (formerly known as hereditary non-polyposis colorectal cancer) is inherited in an autosomal dominant pattern, meaning that an affected individual has a 50% chance of passing it on to their children.
  • Individuals with Lynch syndrome are at high risk of developing a range of cancers (including, most commonly, colorectal and endometrial, as well as ovarian, stomach and others).
  • Patients with Lynch syndrome can be offered personalised risk management, which includes surveillance, risk-reducing surgery, screening for helicobacter pylori and the use of aspirin for chemoprophylaxis.
  • Alert! The lifetime risk of associated cancers can vary significantly depending on the causative gene. It is important to ascertain this prior to making management recommendations.

Example clinical scenario

One of your patients, a 46-year-old woman, has been diagnosed with colorectal cancer. Subsequent tumour testing following NICE guidance suggested Lynch syndrome, and she was referred to clinical genetics services for germline genomic testing. She recently received results showing that she has a pathogenic variant in one of the genes known to cause Lynch syndrome. She attends your practice with a letter from clinical genetics that recommends starting aspirin and being tested for helicobacter pylori infection.

Identifying those at risk of a genetic condition

Lynch syndrome should be suspected if:

  • cancer presents at a young age (below 50);
  • synchronous or metachronous cancer is present (multiple cancers at once);
  • there is a clustering of cancers in a family; and
  • a patient’s cancer is found to be autosomal dominant, with variable penetrance.

Those with specific pathogenic variants do not all carry the same risk of a specific cancer. There are published UK management recommendations for Lynch syndrome, including gene-specific guidelines that show cancer risks according to sex.

What should you do next?

  • Ensure that the cancer diagnosis is coded in the primary care records, including which gene is affected. The purpose of this is to flag that the patient is at high risk of other cancers, and that primary care should have a low threshold to investigate and refer the patient.
  • Refer the patient to local clinical genetics services, who will arrange onward referral to the bowel cancer screening programme.
  • Offer the use of aspirin to reduce the risk of bowel cancer, using the decision aid tool from NICE.
  • Screen and treat for helicobacter pylori. This can reduce stomach cancer risk by 50%.
  • Refer to gynaecology to discuss red flags for cancer and the possibility of risk-reducing surgery at an appropriate age.
  • Emphasise to your patient the importance of having a low threshold for seeking healthcare review, even with vague symptoms, due to the high risk of other cancers.
  • Discuss generic risk reduction with your patient, such as a healthy lifestyle, maintaining a healthy BMI and the avoidance of smoking and excess alcohol consumption.
  • Offer referral to discuss preimplantation genetic testing and other reproductive options.
  • Ensure that your patient has been referred to the local clinical genetics service for support and wider family testing.
  • For information about how to arrange testing in Wales, Scotland or Northern Ireland, see our dedicated Knowledge Hub resource.
  • Information about patient eligibility and test indications were correct at the time of writing. When requesting a test, please refer to the National Genomic Test Directory to confirm the right test for your patient.


For clinicians

For patients

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  • Last reviewed: 05/07/2023
  • Next review due: 05/07/2024
  • Authors: Dr Nicola Robinson
  • Reviewers: Dr Asma Hamad, Dr Johanna Wong