Endometrial Cancer Characteristics and Risk of Recurrence

Objectives To describe clinicopathologic characteristics and survival outcomes of endometrial adenocarcinomas stratified by mismatch repair (MMR) status. Methods Single-institution, retrospective study of all women with endometrioid adenocarcinomas treated from January 2012 through December 2017. Patients were categorized into one of three groups based on MMR testing: intact MMR expression (MMR+), probable MMR mutation (MMR–), or MLH1 hypermethylation (hMLH1+). Demographics, pathologic characteristics, recurrence rates, and survival differences were analyzed. Results In total, 316 women were included in the analysis: 235 (74.4%) patients in the MMR+ group, 10 (3.1%) in the MMR– group, and 71 (22.5%) in the hMLH1+ group. Patients with hMLH1+ were significantly older, exhibited higher-grade histology and presence of lymphovascular space invasion, and were more likely to have received adjuvant treatment. The early stage hMLH1+ patients were more likely to recur (15.3% hMLH1+ vs 2.3% MMR+ vs 12.5% MMR–, P Conclusions Women with hMLH1+ endometrial cancer have worse prognostic features and recur more frequently, even in patients traditionally considered low risk for recurrence.