Mismatch Repair Status is an Effective Prognostic Factor for Early-Stage Endometrial Carcinoma

Abstract

This study is to evaluate the impact of mismatch repair (MMR) status on prognosis among patients with stage I to II (FIGO 2009) endometrial carcinoma (EC) treated with hysterectomy and adjuvant RT. Between Oct. 2017 and Dec. 2020, patients with stage I to II (FIGO 2009) EC who had undergone hysterectomy followed by adjuvant RT in our institution were retrospectively reviewed. Clinical characteristics were compared between patients with proficient and deficient mismatch repair (pMMR and dMMR) using Pearson Chi-Square test for categorical variables. Kaplan-Meier method and log-rank test were used to compared overall survival (OS), disease-free survival (DFS), local-regional recurrence free survival (LRFS) and distant metastasis free survival (DMFS). Statistically significant difference was set as p<0.05. Totally 276 stage I to II EC patients with known MMR status were included in this study. Among them, 211 patients were classified as pMMR while 65 patients were classified as dMMR. When compared to pMMR, patients with dMMR were more likely to have grade 3 and non-endometrioid type(37.8% vs. 20.8%, p = 0.014), lympho-vascular invasion (36.7% vs. 16.3%, p = 0.000), young age (<60) (28.6% vs. 17.2%, p = 0.027), HIR to HR classification(30.9% vs. 16.1%, p = 0.004). Of all the 276 patients, the median follow-up time was 31 months. Two-year DMFS was superior for pMMR compared to dMMR patients (96.3% vs. 95.0%, p = 0.048). Two-year DFS tended to be better for pMMR than dMMR patients with survival curves not crossed over each other (93.0% vs. 86.8%, p = 0.074). Two-year OS (98.9% vs. 98.4%, p = 0.716) and LRFS (96.3% vs. 95.0%, p = 0.815) were not different between pMMR/dMMR patients. For HIR to HR group, we reached the similar conclusion while for LR to IR group, survival statistics were not different between pMMR/dMMR patients. As to failure pattern, dMMR were more likely to have distant failure while local and regional failure were not different between the two groups. For stage I to II EC, patients with dMMR have poorer DMFS and DFS compared to pMMR patients especially in HIR to HR risk classification. The combination of MMR status and other clinical and pathological factors may establish a new prognostic model and form a new risk stratification system.