Prognostic significance of the number of removed lymph nodes according to FIGO stage in ovarian clear cell carcinoma.

A previous study by our group reported that removing a larger number of lymph nodes in patients with stage I ovarian clear cell carcinoma (OCCC) improved progression-free survival (PFS). The present study investigated whether clinical conditions, particularly the number of removed lymph nodes, are independent predictors of progression for stage II or higher OCCC and whether the significance of the number of removed lymph nodes differs according to FIGO stage for OCCC. A total of 113 patients with OCCC who had undergone surgery between January 1993 and December 2015 were retrospectively enrolled and the clinicopathological data were obtained from their medical records. Among patients with stage II or higher OCCC, PFS of those with no residual tumor or no lymph node metastasis was significantly better than that of those with residual tumor (P=0.023) or lymph node metastasis (P=0.035). Multivariate analysis revealed that no residual tumor was the only independent predictor for improved PFS of patients with stage II or higher. Regarding the number of removed lymph nodes, it did not significantly affect the PFS of patients with stage II or higher OCCC, whereas it improved the PFS of those with stage I, being an independent predictor of progression of stage I OCCC. In summary, although the number of removed lymph nodes was an independent predictor of progression for stage I OCCC, it was not for stage II or higher OCCC. The prognostic significance of the number of removed lymph nodes in OCCC may differ depending on the FIGO stage.