Comparative study of ovarian clear cell carcinoma with and without endometriosis in People's Republic of China

OBJECTIVE: To analyze and compare the clinicopathological features and prognosis of ovarian clear cell carcinoma (CCC) with or without endometriosis in Chinese patients. DESIGN: Comparative study based on a retrospective review of medical charts. SETTING: A general university hospital. PATIENT(S): Two hundred ten patients diagnosed and treated with ovarian CCC between 2000 and 2012. INTERVENTION(S): Patients were divided into two groups depending on coexisting endometriosis. A comparison of clinicopathological characteristics was performed. The Kaplan-Meier model and Cox regression were employed in survival analysis. MAIN OUTCOME MEASURE(S): Clinicopathological parameters and survival outcomes. RESULT(S): Of 210 patients, 79 (37.6%) were confirmed to have concurrent endometriosis. Patients with endometriosis were 8 years younger than those without. They were more likely to present at early stage (78.5%) with resectable tumors in primary surgery (with optimal cytoreduction rate at 89.9%) and platinum-sensitive disease (51.7%). Median overall survival for patients with endometriosis was 115 months, an increase of 52 months when compared with 63 months for patients without endometriosis. The 5-year survival rate in patients with endometriosis was 70.2%, while it was 52.6% for those without. Univariate and multivariate analysis showed that coexisting endometriosis was not an independent predictor of survival outcome. Tumor stage and optimal debulking were the independent prognostic factors for both overall survival and progression-free survival. CONCLUSION(S): Patients with ovarian CCC and coexisting endometriosis had distinct clinicopathological features and better survival outcome. However, endometriosis per se did not confer improved survival.