Updated September 2025

Three point of care tools:

1. To identify individuals most likely to benefit from referral to genetics

2. Gene specific cancer risks

3. Gene specific screening recommendations

4. All three tools enclosed here

Bottom line: Lynch syndrome (LS) is a common (1/279) autosomal dominant hereditary cancer predisposition syndrome. LS is associated with an increased lifetime risk for colorectal (CRC) and endometrial (EC) cancer in addition to cancers of the ovary, stomach, small bowel, pancreas, biliary tract, urothelial tissue and renal pelvis, brain (i.e. glioblastoma), and skin (i.e. sebaceous adenoma or carcinoma, keratoacanthomas). The actual cancer risk depends upon which LS-associated gene contains a pathogenic or likely pathogenic variant. Genetic assessment should be considered for those with a:

• Family history of a known pathogenic/likely pathogenic variant in a LS-associated gene (MLH1, MSH6, MSH2, PMS2, EPCAM). All but EPCAM are also known as mismatch repair (MMR) genes.
• Personal history of LS-associated cancer (i.e. CRC, EC or other cancer listed above) diagnosed at <50 years
• Personal history of CRC or EC at any age and a family history of LS-associated cancer, with at least one cancer diagnosed <50 years (the individuals diagnosed with cancer should be related to each other)
• Personal history of CRC or EC and two or more relatives with LS-associated cancers, regardless of age
• Personal history of multiple primary LS-associated cancers
• Personal history of a LS-associated tumour where immunohistochemical (IHC) staining shows deficient mismatch repair (MMR) gene expression, consistent with LS
• Probability of carrying a pathogenic/likely pathogenic variant in a LS-associated gene estimated to be >5%, using a validated risk calculator e.g. PREMM5

Primary care practitioners have a role in identifying those who could benefit from a genetic assessment, coordinating high-risk screening (e.g. annual colonoscopy), and referring for specialist consultation (e.g. gynecology, gastroenterology) for consideration of risk-reducing management and screening recommendations.

(For more information see the GECKO deep dive or the concise GECKO on the run).

Find your local genetics program here.

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