Who should be referred for Lynch Syndrome (LS)?

DNA mismatch repair (MMR) is a system in the body that helps to correct errors in DNA, preventing mutations in DNA. When MMR is not functioning normally, one has a condition known as tumour microsatellite instability (MSI), a condition where ones genes become easily mutated, predisposing to cancer.

MSI and/or immunohistochemical3 (IHC) staining for mismatch repair (MMR) proteins should be considered in:

1. Patient with colorectal cancer (CRC) diagnosed <50 years of age;

2. Patient with CRC that develop at the same time or at different times or other LS-related tumours, regardless of age;

3. Patient with CRC diagnosed <60 years of age with a particular feature known as the MSI-H histology

4. Patient with CRC diagnosed at any age, and who has at least 1 first-degree relative diagnosed with CRC or LS-related tumour diagnosed <50 years;

5. Patient with CRC at any age, and who has 2 or more first- or second-degree relatives with CRC or LS-related tumour at any age.

Referral for testing for mismatch repair genes in the reproductive cells of the patient should be considered when patients have the following:

1. Meets a particular set of factors used to help doctors identify which families are at risk of LS known as the Amsterdam criteria or any of the above listed criteria for tumour MSI or IHC testing for MMR proteins;

2. Endometrial cancer diagnosed <50 years;

3. Known LS genetic change or mutation in family