Comparison between serous and non-serous ovarian cancer as a prognostic factor in advanced epithelial ovarian carcinoma after primary debulking surgery

Residual tumor size after primary surgery is the most important prognostic factor in advanced ovarian cancer. We conducted a retrospective study in Japanese women to evaluate the association of various residual disease diameters and histological subtypes with overall survival (OS) in patients with residual disease ≥1 cm. Demographic and clinicopathological data were obtained from the Tokai Ovarian Tumor Study Group; 294 patients with International Federation of Gynecology and Obstetrics stage III and IV epithelial ovarian carcinoma who had undergone primary debulking surgery between 1986 and 2007 and had ≥1 cm residual tumor were identified. A Cox proportional hazards model was used to assess the association of prognostic factors with OS. Non-serous advanced ovarian cancer was associated with a significant increase in the risk of death. For serous ovarian cancer, residual tumor size was not an independent prognostic factor [multivariate hazard ratio (HR) = 1.63, 95% confidence interval (CI) = 0.96–2.79 (2–5 cm); HR = 1.25, 95% CI = 0.72–2.17 (>5 cm); trend P = 0.480], whereas taxane-based chemotherapy was associated with a better prognosis (HR = 0.66, 95% CI = 0.44–0.99, P = 0.046). For non-serous ovarian cancer, in contrast, residual tumor size was associated with an increased risk of death [multivariate HR = 0.87, 95% CI = 0.36–2.14 (2–5 cm); HR = 2.21, 95% CI = 0.96–5.08 (>5 cm); trend P = 0.067], whereas taxane-based chemotherapy was not a prognostic factor [HR = 0.70, 95% CI = 0.29–1.65, P = 0.409 (taxane-based)]. Although primary maximal cytoreduction is essential to improving OS in advanced ovarian cancer, our findings suggest the management of patients with suboptimal residual tumor should take into account differences between histological subtypes.