Prognosis and adjuvant chemotherapy for patients with malignant peritoneal cytology in early-stage non-endometrioid endometrial cancer

Objective: To investigate the influence of malignant peritoneal cytology (MPC) on the prognosis of early-stage patients with endometrial clear cell carcinoma(CCC) and serous carcinoma(SC), and the value of chemo-therapy in their treatment. Methods: A retrospective observational cohort study was conducted by querying the National Cancer Institute's Surveillance, Epidemiology, and End Results Program from 2010 to 2019. Women with early-stage CCC and SC with available peritoneal cytology results were enrolled. Propensity score matching(PSM) and propensity score inverse probability of treatment weighting (IPTW) was used to balance the measured covariates in each sub-cohort. Results: A total of 3,616 eligible patients were included, and 368 patients had MPC (10.2%). Women with MPC were more likely to receive postoperative chemotherapy (OR 2.033; 95%CI 1.589-2.602). In PSM model, MPC had worse overall survival(OS) and cancer-specific survival (CSS) (All,p < 0.001). The 5-year OS rates were 56.5% for women with MPC and 74.4% for those with negative peritoneal cytology, and the 5-year CSS rates were 60.8% versus 80.0%(All, p < 0.0001). In the subgroup analyses, MPC was associated with decreased OS and CSS in serous, clear cell histology group, and stage IA cases(All,p < 0.001), but not for stage IB or stage II disease. In multivariate analysis, chemotherapy improved the prognosis of patients with MPC(OS:p = 0.005; CSS:p = 0.010). Additionally, in stage IA subgroup, chemotherapy improved survival outcomes in patients with MPC(OS: P = 0.025; CSS:P = 0.038), in NPC patients, however, chemotherapy was a good prognostic factor for OS (P = 0.001) but not for CSS(P = 0.300). Conclusion: MPC was a prognostic factor for decreased survival in early-stage endometrial CCC and SC, and those with MPC could further benefit from chemotherapy.