Significance of Ovarian Endometriosis on the Prognosis of Ovarian Clear Cell Carcinoma.

INTRODUCTION: The aim of this study was to evaluate the significance of ovarian endometriosis on the prognosis of ovarian clear cell carcinoma (OCCC). METHODS: Patients with OCCC were divided into 2 groups according to the presence of ovarian endometriosis: group 1, no coexisting ovarian endometriosis; group 2, clear cell carcinoma arising from ovarian endometriosis or the presence of ovarian endometriosis elsewhere in the ovary. Clinicopathologic characteristics, disease-free survival (DFS), and overall survival (OS) were compared between the 2 groups. RESULTS: Of 155 patients with OCCC, 77 were categorized into group 1 and 78 into group 2. Group 2 patients were younger than group 1 (median age, 48 vs 51 years; P = 0.005) and had higher incidence of early-stage disease (stage I, 77% vs 58%; P = 0.001) and lower incidence of lymph node metastasis (4% vs 17%; P = 0.008). Group 2 patients were observed to have a significantly higher 5-year DFS (P < 0.001) and OS (P = 0.001) compared with group 1. In stage I disease, group 2 had a significantly higher 5-year DFS (P = 0.004) and OS (P = 0.016) than did group 1. In the multivariate analysis, coexisting endometriosis and advanced International Federation of Obstetrics and Gynecology stage were significant factors for both DFS and OS rates. CONCLUSIONS: Ovarian clear cell carcinoma with endometriosis was found more frequently in younger women and had a higher incidence of early-stage disease and a lower incidence of lymph node metastasis compared with OCCC without endometriosis. Ovarian endometriosis was associated with improved prognostic factors and a better DFS and OS even in stage I disease. Ovarian endometriosis was an independent prognostic factor for OCCC.