Prognosis of ovarian clear cell carcinoma compared to other histological subtypes: A meta-analysis

Objective: To compare the survival outcome between clear cell carcinoma (CCC) and other histological subtypes in epithelial ovarian carcinoma (EOC). Methods: From January 1974 to February 2011, we identified a total of 31,800 (CCC; 2152, non-CCC; 29648) patients from 12 studies meeting the inclusion criteria. Results: Heterogeneity tests demonstrated significant between-study variation (I² = 92.1%) with no significant difference in hazard ratio (HR) for death between CCC and non-CCC (HR; 1.16, 95% CI; 0.85-1.57, random-effects model). Comparing the HR based on stage I + II, and stage III + IV, between CCC and non-CCC, showed that CCC patients had a higher hazard rate for death than those with non-CCC of the ovary (stage I + II; HR; 1.17, 95% CI; 1.01-1.36, stage III + IV; HR; 1.65, 95% CI; 1.52-1.79). In a comparison of CCC and serous EOC, advanced stage (III and IV) CCC only showed a poorer hazard rate for death than serous EOC (HR; 1.71, 95% CI; 1.57-1.86). Conclusion: This analysis suggests that ovarian CCC patients had poorer prognosis than those with other histological subtypes of EOC, especially in advanced EOC stages. Different treatment strategies may be needed for patients with ovarian CCC.