Effect of Endometriosis on the Prognosis of Ovarian Clear Cell Carcinoma: A Two-Center Cohort Study and Meta-analysis

Whether endometriosis affects the prognosis of ovarian clear cell carcinoma (OCCC) remains controversial despite the relationship between OCCC and endometriosis. A two-center cohort study and meta-analysis were performed to investigate the effect of endometriosis on the prognosis of OCCC. The study reviewed the clinicopathologic data of 109 patients with OCCC arising (n = 47) or not arising (n = 62) in endometriosis between 1997 and 2012 at two tertiary medical centers. Tumor response and survival were compared between the two groups. For further evaluation, PubMed, EmBase, and the Cochrane Library were searched, and a meta-analysis was conducted using 10 cohort studies published from March 1996 to May 2014, including the current cohort study. Complete response did not differ between the patients with OCCC arising in endometriosis and those without endometriosis (77.5 vs. 87.3 %; P = 0.444). Early-stage disease and optimal debulking surgery were the only independent factors that reduced the risk of noncomplete response (adjusted odds ratios 0.203 and 0.038; 95 % confidence intervals [CIs] 0.045-0.920 and 0.006-0.226, respectively). Progression-free survival (PFS) and overall survival (OS) did not differ between the two groups. Early-stage disease and optimal debulking surgery were the only favorable factors that improved PFS (adjusted hazard ratios [HRs] 0.216 and 0.332; 95 % CIs 0.099-0.469 and 0.150-0.732, respectively) and OS (adjusted HRs 0.099 and 0.339; 95 % CIs 0.039-0.252 and 0.141-0.815, respectively). Furthermore, crude and subgroup meta-analyses showed no effect of endometriosis on PFS or OS in OCCC patients. Endometriosis may not affect the tumor response or the prognosis of OCCC patients.