Genetic and metabolic medicine
Lynch syndrome (hereditary non-polyposis colorectal cancer)
Mismatch repair genes, universal tumour screening and how to read the immunohistochemistry, gene-specific cancer risks, eviQ surveillance, aspirin and risk-reducing gynaecological surgery.
Tier 1Condition
Written with AI assistance and fact-checked against the sources below. For exam study, not clinical decisions. How notes are made
At a glance
- Autosomal dominant germline variant in a mismatch repair (MMR) gene: MLH1, MSH2, MSH6, PMS2, or an EPCAM deletion that silences MSH2. About 1 in 280 people carry one, and most don't know.
- Tumours are mismatch repair deficient (dMMR) with microsatellite instability (MSI-high). This is how most families are found.
- The commonest cancers are colorectal and endometrial. Risk depends strongly on the gene: MLH1 and MSH2 are high risk; MSH6 and PMS2 lower.
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Sources
- eviQ. MMR genes (Lynch syndrome): risk management. Version 14, February 2026AU/NZCancer Institute NSW, 2026
- Clinical practice guidelines for the prevention, early detection and management of colorectal cancerAU/NZCancer Council Australia, 2017, chapters updated
- Seppälä TT et al. European guidelines from the EHTG and ESCP for Lynch syndrome: an updated third edition of the Mallorca guidelines based on gene and gender. Br J Surg 2021;108:484-498European Hereditary Tumour Group and European Society of Coloproctology, 2021
- NCCN Clinical Practice Guidelines in Oncology. Genetic/Familial High-Risk Assessment: Colorectal, Endometrial, and GastricNational Comprehensive Cancer Network, 2026
- Burn J et al. Cancer prevention with aspirin in hereditary colorectal cancer (Lynch syndrome), 10-year follow-up and registry-based 20-year data in the CAPP2 study. Lancet 2020;395:1855-1863The Lancet, 2020
- André T et al. Pembrolizumab in microsatellite-instability-high advanced colorectal cancer (KEYNOTE-177). N Engl J Med 2020;383:2207-2218New England Journal of Medicine, 2020
- Last updated
- 14 November 2026
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