Clinico-pathological significance of suspicious peritoneal cytology in endometrial cancer

Background and Objectives Suspicious peritoneal cytology refers to the result of peritoneal cytology testing that is insufficient in either quality or quantity for a definitive diagnosis of malignancy. This study examined characteristics and survival outcomes related to suspicious peritoneal cytology in endometrial cancer. Methods A population-based retrospective study by querying the National Cancer Institute's Surveillance, Epidemiology, and End Results Program was conducted. A total of 41,229 women with Stage I-III endometrial cancer who had peritoneal cytologic sampling at hysterectomy from 2010 to 2016 were examined. A Cox proportional hazard regression model and a competing risk analysis with Fine-Gray model were fitted to assess survival outcome related to suspicious peritoneal cytology. Results Suspicious peritoneal cytology was seen in 702 (1.7%) cases. In multivariable models, suspicious peritoneal cytology was associated with increased risk of endometrial cancer mortality (subdistribution-hazard ratio [HR] 1.69, 95% confidence interval [CI] 1.29-2.20, p < 0.001) and all-cause mortality (adjusted-HR: 1.55, 95% CI: 1.27-1.90, p < 0.001) compared with negative peritoneal cytology. Sensitivity analysis demonstrated that suspicious peritoneal cytology had discrete overall survival improvement compared with malignant peritoneal cytology in a propensity score weighting model (HR: 0.85, 95% CI: 0.72-0.99, p = 0.049). Conclusion Our study suggests that suspicious peritoneal cytology may be a prognostic factor for decreased survival in endometrial cancer.