Prognostic impact of peritoneal cytology on treating endometrial cancer using data from the Japan Society of Obstetrics and Gynecology cancer registry.

Objective: The prognostic value and clinical usage of peritoneal cytology in endometrial cancer are uncertain. This study aimed to determine whether positive cytology is associated with the prognosis for endometrial cancer.

Methods: A Japanese nationwide retrospective registry study was conducted between 2012 and 2019. Clinicopathological data were analyzed for patients who were registered in the Japan Society of Obstetrics and Gynecology (JSOG) gynecological tumor registry and underwent initial treatment for endometrial cancer.

Results: In total, 83,027 patients who met the inclusion criteria were identified. Data on peritoneal cytology status and overall survival (OS) were available for 74,984 and 36,995 patients, respectively. Positive peritoneal cytology was found in 11,536 (15.4%) patients. A higher proportion of patients who had positive peritoneal cytology were related to advanced stages, high-grade histology, deep myometrial invasion, lymph node (LN) metastasis, and poor risk of recurrence. After controlling for age, stage, myometrial invasion, LN metastasis, distant metastasis, and risk of recurrence, positive peritoneal cytology was associated with poor prognosis (p<0.001). Multivariate Cox regression analysis revealed that clinicopathological factors (i.e., age, International Federation of Gynecology and Obstetrics stage, histological type, myometrial invasion, LN metastasis, distant metastasis, and peritoneal cytology), including positive peritoneal cytology, were also significant prognostic factors for OS.

Conclusion: Positive peritoneal cytology was a prognostic factor for endometrial cancer for the JSOG gynecological tumor registry.