Abstract
BACKGROUND: The prognostic significance of malignant peritoneal cytology (PC) in endometrioid endometrial carcinoma (EC) and its clinical implications for adjuvant therapy selection remain controversial. METHODS: This retrospective cohort study analyzed 9631 endometrioid EC patients from Surveillance, Epidemiology, and End Results (SEER) Program data (2010-2017). Prognostic determinants of overall survival (OS) were identified through Cox regression. Propensity score matching (PSM) generated balanced cohorts: 826 malignant PC, 148 atypical/suspicious PC, and 974 negative PC cases. Survival distributions were compared using Kaplan-Meier analysis. RESULTS: Univariable analysis identified significant OS associations with age, histopathological grade, tumor stage, and PC status (all p < 0.05). Multivariable analysis confirmed malignant PC as an independent prognostic factor. Post-PSM: Malignant PC subgroup showed significantly reduced OS vs others (p < 0.001). Stage-specific effects in malignant PC subgroup: Radiation improved OS only in regional disease (p = 0.016). Systemic therapy reduced OS in all-stage malignant PC (p = 0.022). Atypical/suspicious PC subgroup: No survival benefit from radiation (p = 0.71) or systemic therapy (p = 0.38). CONCLUSION: Malignant PC independently predicts poor prognosis in endometrioid EC but requires cautious interpretation in therapeutic decision-making due to its differential adjuvant therapy effects. PC status alone cannot guide risk stratification; treatment decisions should integrate stage-specific efficacy data. Prospective validation is imperative.