Prognosis of ovarian clear cell cancer compared with other epithelial cancer types: A population-based analysis

In order to compare the clinicopathological characteristics and survival outcomes of patients with ovarian clear cell carcinoma (CCC) to other epithelial cancer types, a total of 27,290 patients were analyzed, including 2,424 patients with CCC (8.9%), 3,505 patients with endometrioid cancer (EC) (12.8%), 2,379 patients with mucinous cancer (MC) (8.7%) and 18,982 patients with serous cancer (SC) (69.6%). Patients with EC had the most favorable prognosis and patients with SC had the poorest prognosis among all epithelial ovarian cancers. Among patients with stage I cancer, patients with CCC had a more favorable prognosis compared with patients with SC, especially after 60 months (landmark analysis results, HR=2.079, P=0.001) and had a poorer prognosis compared with patients with MC [restricted mean survival time (RMST) difference, −3.434 months]. Among patients at stages III and IV, patients with CCC had a poorer prognosis compared with patients with SC (RMST difference in stage III, −7.588 months; RMST difference in stage IV, −15.445 months) and had a more favorable prognosis compared with patients with MC (RMST difference in stage III, 10.850 months; RMST difference in stage IV, 8.430 months). The present results suggested that most patients with CCC exhibited, high grade, an early stage, unilateral status and were of a young age. In general, patients with SC presented the poorest prognosis among all patients with epithelial ovarian cancer and no significant survival difference was found between patients with CCC and MC. However, after adjusting for stage using pairwise comparisons, the prognosis of patients with CCC was found to be more favorable compared with the patients with SC and worse compared with patients with MC at stage I; the results at stage III–IV were opposite and the prognosis of patients with CCC was worse compared with the patients with SC and more favorable compared with the patients with MC.