A comparison of ascertainment of Lynch syndrome in colorectal cancer patients via reflex testing vs. hereditary guideline-based testing.

1517 Background: In accordance with The American College of Medical Genetics and Genomics (ACMG), many institutions including The Hereditary Cancer Program (HCP) of the B.C. Cancer Agency recommend initiating testing for Lynch Syndrome (LS) based on the Bethesda criteria and/or on an age threshold of less than 50 years. Reflex immunohistochemical (IHC) testing independent of family history to infer deficient Mismatch Repair (dMMR) status combined with mutant BRAF 600E (mBRAF) IHC assessment provides an alternative means of screening for LS. Although many centers have adapted a reflex approach to screening for LS, this approach is still not standard. This study compares the efficacy of the two methods. Methods: From January 2012 to July 2013, reflex IHC testing to detect dMMR and mBRAF was performed in all cases of resected CRC across different jurisdictions in the greater Vancouver catchment area. Additional characteristics such as age at diagnosis, personal history of cancer, family history of cancer, an...