Lynch syndrome (LS), driven by germline pathogenic variants in the DNA mismatch repair (MMR) genes (MLH1, MSH2, MSH6, PMS2, and EPCAM deletions), is classically associated with MMR-deficient (MMR-D) or microsatellite instability–high (MSI-H) colorectal cancer (CRC). These tumors carry prognostic and therapeutic significance: improved outcomes relative to microsatellite stable disease, lack of benefit from fluorouracil-based adjuvant chemotherapy, and strong predictive value for response t...
