Lymph node ratio has impact on relapse and outcome in patients with stage III melanoma

Even though both the involvement of regional lymph nodes and the number of metastatic lymph nodes are regarded as major determinants of survival in cutaneous melanoma, the extent of node dissection has been analyzed as an independent prognostic indicator in only a few studies. This study aims to determine how the lymph node ratio (NR) (ratio of positive nodes to total nodes removed) might predict the disease relapse and survival in node-positive melanoma.

A total of 317 patients with stage III primary melanoma were included in the study and reviewed retrospectively. All patients had nodal staging (N) by radical lymph node dissection. Patients were divided into three groups based on NR1 ≤ 10%, NR2 10-25%, and NR3 > 25%.

The median age was 50 years (range 16-86) and men were predominant (59.3%). The majority of the patients had thicker Breslow depth (> 2 mm) (83.3%), higher mitotic rate (> 2/mm²) (64.1%) and ulcerated lesions (69.4%). The median number of positive nodes was 1 (range 1-32). The largest group was N1 (52.4%), which was followed by N2 (29.6%) and N3 (18%). The ratios of patients were 37.5%, 35.3%, and 27.1% in NR1, NR2, and NR3, respectively. The median number of excised lymph nodes was 13 (range 1-73). For all patients the estimated 5-and 10-year relapse-free survival (RFS) rates were 41% and 39%, respectively; and the estimated 5-and 10-year overall survival (OS) rates were 51% and 42%, respectively. Nodular histopathology, ulcerated lesions, higher mitotic rates, and higher node substages were the independent variables that were inversely correlated with survival for all patients; and NR was one of the significant prognostic factors and strongest predictors of relapse and survival (p = 0.03 and p = 0.01, respectively).

Our results suggest that, apart from the conventional nodal status, NR is an independent prognostic factor-regarding both RFS and OS in stage III cutaneous melanoma.