Role of sentinel lymphadenectomy in thin cutaneous melanomas with positive deep margins on initial biopsy.

ABSTRACT

INTRODUCTION: Breslow thickness (BRES) on initial melanoma biopsy determines need for sentinel lymph node (SLN) biopsy. In presence of positive deep margins, BRES is indeterminate. We hypothesized that thin (BRES <0.76 mm) melanomas with positive deep margins and thicker melanomas (BRES 0.76-2.0 mm) have statistically similar risk of SLN metastasis. METHODS: Retrospective review was performed of adult patients undergoing wide excision plus SLN biopsy for melanoma from 01/2004 to 05/2010. Group 1 (BRES <0.76 mm and positive deep margins) was compared to Group 2 (BRES 0.76-2.0 mm, regardless of margin status). Primary outcome was presence of SLN metastasis. RESULTS: 260 patients were eligible, 72 (28%) in Group 1 and 188 (72%) in Group 2. Average age was 57 years, with 120 (46%) females. SLNs were positive in 6/72 (8.3%) patients in Group 1 and 17/188 (9.0%) patients in Group 2 (P=0.86). The two groups were not statistically different by multivariate analysis (P=0.49). In multivariate model, Clark's level IV (P=0.009) was only predictive factor of SLN metastasis. CONCLUSIONS: Melanoma patients with thin BRES but positive deep margins carry risk of SLN metastasis similar to patients with thicker melanomas. Positive deep margins should be considered in decision to perform SLN biopsy. Clark's level IV was significantly associated with SLN metastasis.