Endometriosis-associated Ovarian Cancer: A Distinct Clinical Entity?

Aim: The aim of the study was to evaluate the incidence of endometriosis-associated ovarian cancer (EAOC) and compare clinicopathological characteristics and overall survival (OS) between patients with EAOC and those with ovarian cancer not associated with endometriosis. Patients and Methods: We identified EAOC among 203 patients with invasive epithelial ovarian cancer who underwent complete surgery at our Institution from January 2004 to March 2014. Results: EAOC was present in 45 patients. EAOC was significantly more frequently diagnosed at an earlier stage of disease (p=0.038). At a median follow-up time of 32 months, OS among patients with EAOC was significantly longer (p=0.039). However, stratifying by stage, the OS advantage of EAOC was not significant. At multivariate analysis, only stage was an independent prognostic factor for OS (hazard ratio=5.7; 95% confidence interval=1.8-18.6; p=0.003). Conclusion: EAOC incidence was 22.2%. EAOC appears to be diagnosed at an earlier stage and confers a better OS. However, stratifying by stage, the advantage in survival of EAOC disappears.