EP550 Prognosis trend of grade 2 endometrioid endometrial carcinoma: toward grade 1 or 3?

Introduction/Background The prognostic significance of grade in the endometrial cancer is well known. However, grade 2 cases were not evaluated separately in most of the previous studies. In this study, we aimed to investigate whether the oncologic outcomes of grade 2 endometrioid endometrial carcinomas is trending to grade 1 or 3 tumors. Methodology Patients records and pathological reports were reviewed retrospectively and 776 patients of endometrioid endometrial carcinoma were distributed into 3 groups according to their 1988 FIGO grade. Groups9 characteristics and oncologic outcomes were compared. Difference between grades was tested with z-test and adjusted by Bonferroni method. Kaplan-Meier method were performed for the survival analysis. Results Mean follow-up time was 52 months. Patients9 mean age was 56.29±10.8 years. Five years OS, DFS rates were 95.1%, 83.3% and 91.6%, 79.1% for grade 1 and 2, respectively. These rates were not statistically different (OS: p=0.075, DFS: P=0.939). The statistically difference between grade groups in terms of OS and DFS was mainly noticed between grade 1 and 3 (OS: 75.6%, DFS: 60.3%) Even though, grade 2 endometrioid endometrial carcinomas were different from both grade 1 and 3 in terms of the pathological features, survival analyses demonstrated that their oncologic outcomes were trended to grade 1. Grade was determined as an independent prognostic factor for OS. Conclusion The interobserver reproducibility will be improved among pathologists by combining FIGO grade 1 and 2 endometrioid endometrial carcinomas, while prognosis prediction would not likely to be affected. Disclosure Nothing to disclose.