MRC1 and Lynch syndrome: A single-center study found 21% of nonserous epithelial OC to be MMR deficient by IHC.21 Lynch syndrome–associated OC is predominantly endometrioid, presenting at an earlier age and stage than sporadic OC, with improved survival rates.22 Lynch syndrome is found in 7% of women with synchronous EC and OC.23 Many professional organizations now recommend testing all epithelial OC patients for BRCA1/2 pathological variants.24,25 Given the similar cumulative risk of OC in Lynch syndrome, testing premenopausal women with epithelial OC for both BRCA1/2 and Lynch syndrome is appropriate.