Prognosis Trend of Grade 2 Endometrioid Endometrial Carcinoma: Toward Grade 1 or 3?

Although the prognostic significance of grade in endometrial cancer is well known, grade 2 cases have not been evaluated separately in most of the previous studies. In this study, we aim to investigate whether the oncologic outcomes of grade 2 endometrioid endometrial carcinomas trend towards grade 1 or 3 tumors. Patients' records and pathological reports were reviewed retrospectively and eligible patients with endometrioid endometrial carcinoma were determined and distributed into 3 groups according to their 1988 International Federation of Gynecology and Obstetrics (FIGO) grade. Groups' characteristics and oncologic outcomes were compared. Differences between grades were tested with z-test and adjusted by Bonferroni method. Kaplan-Meier method was performed for the survival analysis. In total, 776 patients of endometrioid endometrial carcinoma were included in this study. Mean follow-up time was 52 ± 14 months. Patients' mean age was 56.3 ± 10.8 years. 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 trended towards grade 1. The grade was determined as an independent prognostic factor for overall survival (OS). The interobserver reproducibility will be improved among pathologists by combining FIGO grade 1 and 2 endometrioid endometrial carcinomas, while prognosis prediction is not likely to be affected.