Prognostic Relevance of Uncommon Ovarian Histology in Women With Stage III/IV Epithelial Ovarian Cancer

Abstract

The prognostic relevance of uncommon epithelial ovarian cancer (EOC) histological subtypes remains controversial. The Gynecologic Cancer InterGroup (GCIG) initiated this meta-analysis to assess the relative prognosis of women with a diagnosis of rare EOC histologies from completed, prospectively randomized studies performed by cooperative GCIG study groups. Studies eligible for analysis included first-line treatment of at least 150 patients with stage III/IV EOC treated with a platinum/taxane-based regimen. Collaborating groups were to provide patient-level data. Serous acted as the reference histology, and a proportional hazards model was used to estimate the relative rate of progression or death. Data on 8704 women with stage III/IV EOC from 7 randomized trials were included in these analyses. Two hundred twenty-one patients (2.5%) had clear cell carcinoma; 264 (3.0%), mucinous; and 36 (0.4%), transitional cell. The mean age of patients with serous histology was greater than those with mucinous (4.1 years) and clear cell (2.6 years, P < 0.001). Mucinous, clear cell, and transitional cell tumors were more likely to be completely resected than serous (P < 0.05). When controlling for age and residual disease, mucinous and clear cell tumors had shorter times to progression (hazards ratio [HR], 2.1; 95% confidence interval [CI], 1.8-2.4 and HR, 1.6; 95% CI, 1.4-1.9, respectively) and death (HR, 2.7; 95% CI, 2.3-3.1 and HR, 2.2; 95% CI, 1.8-2.6, respectively) compared with serous. The median overall survival for serous, clear cell, mucinous, and endometrioid histologies were 40.8, 21.3, 14.6, and 50.9 months. Mucinous and clear cell carcinomas are independent predictors of poor prognosis in stage III/IV EOC. Studies targeting these rare histological subtypes are warranted and will require significant intergroup collaboration.