556P Prognostic significance of positive peritoneal cytology in endometrial carcinoma based on ESGO/ESTRO/ESP risk classification: A multicenter retrospective study

Abstract

Since the International Federation of Gynecology and Obstetrics (FIGO) removed positive peritoneal cytology (PC) from the staging system in 2009, the prognostic significance of PC in endometrial carcinoma (EC) remains controversial. The objective of this study was to determine the prognostic significance of positive-PC on ESGO/ESTRO/ESP risk classification. This study included EC patients with available PC results from 30 medical centers in China from 2000 to 2019. Patients were divided into three prognostic risk groups according to the risk classification: low-risk, Intermediate-risk and high-intermediate risk, and high-risk groups. Propensity score inverse probability of treatment weighting (PS-IPTW) was used to balance covariates. The prognostic significance of PC was assessed by Kaplan–Meier curves and multivariate Cox regression analysis for progression-free survival (PFS) and overall survival (OS). A total of 6313 EC patients met the inclusion criteria, and positive-PC was reported in 384 women (6.1%). Positive-PC was independently associated with decreased PFS (adjusted-HR 2.23, 95%CI 1.57-3.14, P<0.001) and OS (adjusted-HR 2.29, 95%CI 1.53-3.44, P<0.001) on multivariate COX analysis in all patients. IPTW-adjusted Kaplan-Meier curves showed a poor survival outcome for positive-PC compared to negative-PC in the intermediate and high-intermediate risk group (5-year PFS: 75.5% versus 93.0%, P<0.001; 5-year OS: 78.3% versus 96.4%, P<0.001). While in the low-risk group, there were no significant differences in PFS and OS between the two groups (5-year PFS: 93.1% versus 97.3%, P=0.124; 5-year OS: 98.6% versus 98.2%, P=0.823). In the high-risk group, significant difference was only found in PFS (5-year PFS: 62.5% versus 77.9%, P=0.033; 5-year OS: 71.3% versus 81.0%, P=0.071). Positive-PC was an adverse prognostic factor for EC, especially in the intermediate-risk and high-intermediate groups. Gynecologic oncologists should consider the prognostic effect of positive-PC on different ESGO risk groups, and carefully make clinical decisions or recommend appropriate adjuvant therapy.