Prognostic implications of multiple lymphatic basin drainage in patients with truncal melanoma

Lymphatic drainage to multiple basins (MLBD) is frequently observed in patients with truncal melanoma undergoing sentinel lymph node (SLN) mapping. Recently published data suggest that patients with MLBD are at increased risk of nodal metastases compared with those with single lymphatic basin drainage (SLBD). We studied the impact of MLBD on SLN positivity and survival.

We identified 266 patients with truncal melanoma undergoing SLN mapping and biopsy from 1995 to 2001. MLBD was defined as lymphoscintigraphic and intraoperative identification of an SLN in more than one nodal basin. Clinical and pathologic variables were recorded and analyzed for their impact on survival.

MLBD occurred in 76 patients (29%), and SLBD occurred in 190 patients (71%). Clinical and pathologic variables were similar between the two groups, although there were more males in the MLBD group (78% v 64%; P = .034). Patients with MLBD did not have higher risk for positive SLNs compared with those with SLBD (22% v 21%, respectively). Five-year survival for patients with MLBD was less favorable than that of patients with SLBD (68% v 78%, respectively; log-rank P = .04). Multivariate analysis revealed that increasing Breslow thickness (P < .001), SLN metastasis (P < .001), and MLBD (P = .04) were independent predictors of poor overall and relapse-free survival. The negative prognostic implication of MLBD remained significant when only patients with negative SLNs were analyzed (relative risk, 2.7; P = .03).

MLBD in patients with truncal melanoma undergoing SLN mapping is associated with a less favorable survival compared with patients with SLBD, independent of SLN status.