Pasanen A, et al. - In this study, the prognostic and clinicopathologic differences were determined between methylation-linked and nonmethylated MMR-deficient endometrioid endometrial carcinoma (EC). Researchers conducted MMR immunohistochemistry and methylation-specific multiplex ligation-dependent probe amplification, and classified 682 unselected endometrioid ECs as MMR proficient (MMRp, n = 438) and MMR deficient (MMRd, n = 244), with the latter subcategorized as methylated (MMRd Met) and nonmethylated tumors. The evidence showed that MMR methylation profile associates with clinicopathologic characteristics of endometrioid EC, and MMRd-Met phenotype predicts lower disease-specific survival. It was reported that MMR deficiency, but not MLH1 methylation status, associates with T-cell inflammation and PD-L1 expression.