Positive peritoneal cytology is an independent risk-factor in early stage endometrial cancer

Objective: In light of the recent changes in the International Federation of Gynecology and Obstetrics (FIGO) staging system, the objective of this study was to determine the prognostic significance of positive peritoneal cytology (PPC) among patients with early stage endometrial cancer. Methods: Data were extracted from the Surveillance, Epidemiology, and End Results database between 1988 and 2005. Only those patients with stage I/II endometrial cancer who had undergone a complete staging procedure (lymph-node removal) were included. Statistical analyses used Chi-square test, Kaplan-Meier log rank, and Cox proportional hazards models. Results: A total of 14,704 patients were identified: 14,219 with negative peritoneal cytology (NPC) and 485 with positive peritoneal cytology. More patients with PPC compared to those with NPC were diagnosed with high-risk factors such grade III disease (40.2% vs. 23.8%, p < 0.0001), and unfavorable histologic types such as clear cell/serous carcinoma (17.5% vs. 7.5%, p = < 0.0001) and carcinosarcoma (9.3% vs. 5.6%, p < 0.0001). When compared to patients with negative peritoneal cytology, survival was significantly worse among patients with positive peritoneal cytology (p < 0.0001): 5-year disease specific survival 95.1% vs. 80.8% in endometrioid adenocarcinoma; 78.0% vs. 50.4% in clear cell/serous cancer; and 64.7% vs. 32.3% in carcinosarcoma. After adjusting for other contributing factors in the multivariable model, PPC remained an independent predictor of poor survival (p < 0.0001) in all histologic types examined. Conclusion: PPC is an independent risk factor in patients with early stage endometrial cancer. Although, no longer a part of the current FIGO staging criteria, peritoneal cytology status should still be considered for accurate risk-stratification of these patients.