Clinical Characterization Of Dna Mismatch Repair Deficiency (Mmr-D) In Endometrial Cancer (Ec).

1522Background: MMR-D, characterized by loss of protein expression of MMR protein(s) (MLH1, MSH2, MSH6, PMS2) by immunohistochemistry (IHC) occurs in 20-25% of ECs u0026 serves as a screening test for Lynch Syndrome (LS). MMR-D may be somatic, characterized by MLH1/PMS2 protein loss u0026 presence of MLH1 promoter hypermethylation (MLH1-HM+) or may result from a germline mutation in a MMR gene (LS). However, a proportion of MMR-D EC patients (pts) have absence of an identifiable germline alteration u0026 absence of MLH1-HM and are referred to as having “Lynch-like syndrome” (LLS). Clinical u0026 family history (hx) of LLS in EC remains poorly characterized. Methods: Database review identified all MMR-D EC pts who were evaluated at MSKCC 2007-2015. Electronic medical records u0026 progeny pedigrees were reviewed. Statistics performed via GraphPad Prism v. 6, Mann Whitney U compared median age, Fishers exact test was performed on remaining variables. Results: Of 226 MMR-D EC cases, 101 (45%) had MLH1/PMS2 loss with MLH1-HM+, 6...