Impact of Positive Peritoneal Cytology on Prognosis in Stage IA Endometrial Cancer: A Retrospective Cohort Study in the Era of Minimally Invasive Surgery.

Objective: The prognostic significance of positive peritoneal cytology (PC) in early-stage endometrial cancer remains debated, particularly following its exclusion from the 2008 International Federation of Gynecology and Obstetrics (FIGO) staging system. This study aimed to evaluate the impact of positive PC on recurrence and survival outcomes in patients with stage IA endometrial cancer, considering contemporary surgical practices, including minimally invasive surgery.

Methods: This retrospective cohort study included 325 patients diagnosed with stage IA endometrial cancer who underwent primary surgical treatment at Kagoshima University Hospital between 2010 and 2022. PC was assessed intraoperatively, and patients were stratified into positive and negative cytology groups. Clinicopathological characteristics, recurrence-free survival (RFS), and overall survival (OS) were compared using Kaplan‒Meier analysis. Cox proportional hazards regression was performed to identify independent prognostic factors.

Results: Positive PC was identified in 5.8% (19/325) of cases. Patients with positive cytology had significantly lower five-year RFS (72.7% vs. 93.7%, p = 0.0001) and OS (82.1% vs. 96.1%, p = 0.0001). Cox regression analysis identified positive PC as the strongest independent predictor of recurrence (HR 8.33, 95% CI: 2.41-25.8) and mortality (HR 14.2, 95% CI: 2.22-90.3). In addition, advanced age (≥60 years) was significantly associated with decreased survival.

Conclusions: Positive PC is a significant adverse prognostic factor in stage IA endometrial cancer, associated with increased recurrence and reduced survival. Future large-scale prospective studies are needed to determine its role in risk stratification and management of stage IA endometrial cancer.