Objective The objective of this study was to elucidate factors that affect prognosis in patients with stage I endometrial cancer.

Methods The study group comprised 265 patients with stage I endometrial cancer treated surgically at either of our facilities between January 1998 and December 2010 (238 patients with negative peritoneal cytology and 27 patients with positive peritoneal cytology). Progression-free survivals were evaluated between the 2 groups, and multivariate analysis was conducted with correlation factors including positive peritoneal cytology, vessel permeation, lymph node dissection, histologic diagnosis, age at diagnosis, adjuvant chemotherapy, and the depth of myometrial invasion.

Results Disease-free survival was significantly poorer for patients with positive peritoneal cytology than those with negative peritoneal cytology on stage I disease (P = 0.000). The stratified log-rank test with vessel permeation shows the similar results. By univariate Cox model, positive peritoneal cytology, vessel permeation, and systemic lymph node dissection at surgery are significant factors on stage I endometrial cancer.

Conclusions Although this is a small-scale preliminary study with adjustment of other factors, positive peritoneal cytology can contribute to the risk of progression-free survival in patients with stage I endometrial cancer.