Lymph node ratio is an important and independent prognostic factor for patients with stage III melanoma.

Introduction: The incidence of melanoma is dramatically increasing worldwide. We hypothesized that the ratio of metastatic to examined lymph node ratio (LNR) would be the most important prognostic factor for stage III patients.

Methods: We retrospectively reviewed our institutional database of melanoma patients and identified 168 patients who underwent lymph node dissection (LND) for stage III disease between 1993 and 2007. Patients were divided into three groups based on LNR (≤10%, n = 93; 10-≤25%, n = 45; and >25%, n = 30). Univariate and multivariate analysis was performed using Cox proportional hazards model.

Results: The median survival time of the entire group of patients was 34 months. The median number of positive nodes was 2 (range = 1, 55), and the median number of examined nodes was 22 (range = 5-123). Tumor characteristics of the primary melanoma (such as thickness, ulceration, and primary site) were not significant predictors of survival in this analysis. By univariate analysis, LNR was an important prognostic factor. Patients with LNR 10-25% and >25% had decreased survival compared to those patients with LNR ≤10% (HR = hazard ratio = 2.0 and 3.1, respectively; P ≤ 0.005). The number of positive lymph nodes also impacted on survival (P = 0.001). In multivariate analysis, LNR of 10-25% and >25% predicted survival (HR = 2.5 and 4.0, respectively).

Conclusion: LNR is an important prognostic factor in patients undergoing LND for stage III melanoma. It can be used to stratify patients being considered for adjuvant therapy trials and should be evaluated using a larger prospective database.