Impact of the number of removed lymph nodes on recurrence-free survival in stage I ovarian clear cell carcinoma.

BACKGROUND: Although there have been several reports regarding the significance of staging lymphadenectomy for early stage ovarian clear cell carcinoma (CCC) patients, there have been few reports focusing on the number of removed lymph nodes. The aim of this study was to evaluate the impact of the number of removed lymph nodes on recurrence-free survival (RFS) in stage I ovarian CCC. METHODS: The subjects were patients with ovarian CCC who underwent surgery between January 1988 and December 2013. Clinicopathological variables were obtained from the medical records retrospectively. Statistical analysis using Kaplan-Meier method, log-rank test, and Cox proportional hazards model was performed. RESULTS: A total of 68 patients were entered into this study. The median number of removed lymph nodes was 56.5 (21-135). We calculated that the cutoff value of the number of removed lymph nodes for predicting recurrence was 35. RFS of the group with ≥ 35 removed lymph nodes was significantly better than that of the group with < 35 removed lymph nodes (p = 0.001). Similarly, RFS of stage IA and PS 0 or 1 was significantly better than that of stage IC (p = 0.029) and PS 2 or 3 (p = 0.001), respectively. Multivariate analysis revealed that the number of removed lymph nodes, stage, and PS was independent predictors for RFS. CONCLUSIONS: This study showed that the number of removed lymph nodes ≥ 35 was an independent predictor for improved RFS for stage I ovarian CCC. Sufficient lymphadenectomy may improve prognosis for stage I ovarian CCC.