Objective This study aimed to analyze the clinicopathological features of pure and mixed-type ovarian clear cell carcinoma (CCC) in Chinese patients.

Methods Patients with ovarian CCC treated in our institution between 1982 and 2012 were identified by reviewing the database and medical charts. Patients were assigned into 2 groups based on histology (pure or mixed). Comparison of clinicopathological parameters was performed to determine the similarities and/or differences between pure and mixed CCC. Kaplan-Meier model was used in survival analysis.

Results Of 341 patients with ovarian CCC, 46 (13.5%) mixed tumors were identified, and the most common combination was clear cell/endometrioid, accounting for 56.5%. Patients with mixed-type CCC tended to have higher level of serum cancer antigen 125 (P = 0.023) and advanced tumor stage (P = 0.001). No difference was observed in other features including age, tumor size, residual disease, lymph node metastasis, and coexisting endometriosis. Tumor recurrence occurred in 47.8% and 58.1% in patients with pure and mixed histology, respectively (P = 0.209). Two groups had comparable platinum-sensitive disease (42.1% in pure and 44.0% in mixed type, P = 0.860). Patients with pure CCC had an improved median survival (105 vs 56 months), although statistical significance was not achieved. Histology subclassification of mixed tumor revealed that patients with clear cell/endometrioid histology had better survival outcome than those with clear cell/serous type (median survival, 140 vs 43 months, P = 0.004; median progression-free survival, 49 vs 12 months, P = 0.001).

Conclusions Patients with mixed CCC tended to have elevated serum cancer antigen 125 and advanced tumor stage. However, no significant difference was observed between the pure and mixed tumors regarding prognosis.