Endometriosis-related ovarian cancer risk and prognosis: A meta-analysis.

e15525 Background: The association between ovarian cancer and endometriosis has not been well established in previous studies. We investigated the impact of endometriosis on the development of ovarian cancer (OC) and prognosis in patients with OC using a meta-analysis. Methods: After we performed a MEDLINE search to identify all relevant studies between March 1945 and December 2010, we found 4 studies (2 case-control, 2 cohort; n=157,292) related with OC risk and 4 studies (1 case-control, 3 cohort; n=46,716) associated with prognosis in patients with OC among 2,402 potentially relevant studies. This meta-analysis was performed using the fixed-effect model because of no heterogeneity. Results: Endometriosis increased the risk of OC (RR, 1.25; 95% CI, 1.14-1.37). Although endometriosis did not influence the risk of OC in two cohort studies (RR, 1.30; 95% CI, 1.01-1.68), two case-control studies showed that endometriosis was associated with the increased of OC (RR, 1.24; 95% CI, 1.12-1.36). On the other hand, endometriosis-associated OC (EAOC) showed improved overall survival (OS) when compared with non-EAOC (HR, 0.77; 95% CI, 0.64-0.92). In sub-analyses based on the design of study, one case-control study demonstrated that EAOC was associated with improved OS (HR, 0.56; 95% CI, 0.36-0.87), and EAOC was also related with improved OS with marginal significance when compared with non-EAOC (HR, 0.82; 95% CI, 0.67-1.00) in three cohort studies. Conclusions: These findings suggest that women with endometriosis may have a higher risk of OC than those without endometriosis, whereas coexistent endometriosis may be associated with improved OS in patients with OC.