Hampel H, Pearlman R, de la Chapelle A, et al. - Among endometrial cancer patients enrolled in the Ohio Colorectal Cancer Prevention Initiative, researchers undertook this investigation to ascertain the relative frequency of Lynch syndrome and double somatic mismatch repair (MMR) pathogenic variants (PV). They found 27% (91/341) of tumors were either MSI(microsatellite instability)-high or exhibited abnormal immunohistochemical staining suggesting dMMR (MMR-deficiency). As expected, the presence of MLH1 methylation was detected in most dMMR tumors. Findings demonstrated that in endometrial cancer patients, double somatic MMR gene PV were as common as Lynch syndrome, and therefore, the most efficient approach for LS screening may be paired tumor and germline testing for patients with non-methylated dMMR tumor.