Metastasis of primary melanoma to two separate lymph node basins: Prognostic significance

Background and Methods: Depending on the location of the primary lesion, melanoma patients may develop metastases in more than one regional lymph node basin. To determine whether this is prognostically significant, we reviewed our experience with melanoma patients who had undergone regional lymphadenectomy (RLND) in two separate basins. Results: Of 3,603 patients who underwent RLND between April 1971 and January 1993, 406 underwent procedures in two separate basins; of these, 120 (30%) had metastases in both basins and 124 (30%) had metastases in one basin. When calculated from the first positive RLND, 1-year, 3-year, and 5-year survival rates were 82%, 48%, and 33%, respectively, for patients with dual-basin involvement and 88%, 59%, and 48%, respectively, for patients with single-basin involvement (p = 0.0173). Median survival from the first positive RLND was 33.5 months for dual-basin involvement and 56.6 months for single-basin involvement. Univariate analysis demonstrated that Breslow thickness of the primary melanoma, clinical status of the regional lymph nodes, number of positive RLNDs, and tumor burden (total number of positive lymph nodes) were significant indicators of survival. The patient's age and gender, the anatomic location and Clark level of the primary melanoma, the disease-free interval before regional metastasis, and the site and timing of RLNDs were not significant by univariate analysis. Multivariate analysis demonstrated significance for Breslow thickness, number of positive RLNDs, and tumor burden. Conclusions: The survival rate of melanoma patients with regional metastases in two lymph node basins is lower than that of patients with an equal tumor burden confined to a single basin. This suggests that primary melanomas metastasizing to more than one lymph node basin may have a higher metastatic potential, or that dual-basin involvement may increase the risk of systemic spread. We advocate lymphatic mapping, sentinel node biopsy, and selective lymphadenectomy as a cost-effective technique with little morbidity to identify and manage occult metastases in patients who have two lymph basins at risk.