Impact of multiple lymphatic channel drainage to a single nodal basin on outcomes in melanoma.

OBJECTIVE To determine the impact of multiple lymphatic channels (MLCs) on outcome in melanoma. DESIGN Retrospective cohort study. SETTING Academic tertiary care center. PATIENTS Of 1198 consecutive selective sentinel lymphadenectomies performed from 1995 to 2000 for primary invasive melanoma, 502 patients were identified with extremity or truncal melanoma that drained to a single nodal basin. Three cohorts were formed based on lymphatic channels (none, single, and multiple). Tumors with drainage to multiple nodal basins as well as all head and neck tumors were excluded. MAIN OUTCOME MEASURES Multiple variables, including patterns of lymphatic drainage, were analyzed for impact on disease-free and overall survival. RESULTS Demographics were similar among groups, with a median follow-up of 5.6 years. Univariate analysis revealed MLCs as an independent risk factor for both disease-free (P = .04) and overall survival (P = .003). Multivariate analysis confirmed that tumor depth, sentinel lymph node status, and MLCs were risk factors for both disease-free and overall survival. Kaplan-Meier analysis showed worse survival in the MLCs group. CONCLUSIONS Our study reveals that MLCs are an independent risk factor for recurrence and mortality in melanoma. Multiple lymphatic channels may facilitate the process of metastasis.