Figure 1

Flow diagram of Lynch syndrome (LS) screening conducted among patients in the study sample. *LS screening indicates any guideline-recommended combination of genomic MSI and/or protein immunohistochemistry (IHC) tests, germline mutation analysis of MLH1, MLH2, MLH6, and PMS2 genes, and MLH1 hypermethylation studies and BRAF testing to detect sporadic MMR defects (refs. ^5,7,11). ^†Further testing is not indicated when tumors are MSI-L or MSI-S, or when all gene protein products are present on IHC because patients are assumed not to have LS (refs. ^4,20,37,38). ^‡Further testing is not indicated in the case of MLH1 methylation or BRAF v600E mutation because patients are assumed to not be at risk for LS (refs. ^3,5,7). MMR, mismatch repair; MSI-H indicates microsatellite instability high; MSI-L indicates microsatellite instability low; MSI-S indicates microsatellite instability stable.