Do clear cell ovarian carcinomas have poorer prognosis compared to other epithelial cell types? A study of 1411 clear cell ovarian cancers

Objective: To compare the clinico-pathologic characteristics and survival of women with clear cell versus other epithelial ovarian cancers. Methods: Data were obtained from the Surveillance, Epidemiology and End Results Program between 1988 and 2001 and analyzed using Kaplan-Meier and Cox proportional hazards models. Results: Of 28,082 women with epithelial ovarian cancer, 1411 (5%) had clear cell, 13,835 (49.3%) papillary serous, 3655 (13%) endometrioid, 2711 (9.7%) mucinous, and 6470 (23%) had unspecified histologies. The median age of overall patients was 64 years; with clear cell patients presenting at younger age (55 years). The proportion of clear cell histology was significantly higher in Asians versus Whites, Blacks, and others (11.1% versus 4.8%, 3.1%, and 5.5%; p < 0.001). Clear cell carcinoma is more likely to be diagnosed at early-stage (67.3%) compared to 19.2% in serous, 61.6% endometrioid, and 61.3% in mucinous carcinomas (p < 0.005). Retroperitoneal lymph node metastases were found in 13.6% of serous carcinomas, 7.9% clear cell, 7.3% endometrioid, and 3.8% of mucinous (p < 0.001). Adjusted for stage, the 5-year disease-specific survival of patients with clear cell carcinoma is worse compared to serous: 85.3% vs. 86.4% for stage I, 60.3% vs. 66.4% stage II, 31.5% vs. 35.0% stage III, and 17.5% vs. 22.2% for stage IV, respectively (p < 0.001). On multivariate analysis, age, stage, grade, histology, and surgical treatment were independent predictors of disease-specific survival. Conclusions: Our data suggest that women with clear cell ovarian cancer present at a younger age, are more likely to be Asian, and have a poorer prognosis compared to serous cancers.