Patterns of recurrence after sentinel lymph node biopsy for cutaneous melanoma.

Background: Previous sentinel lymph node (SLN) studies for cutaneous melanoma have shown that the SLN accurately reflects the nodal status of the corresponding nodal basin. However, there are few long-term studies that describe recurrence site patterns, predictors for recurrence, and overall survival and disease-free survival after SLN biopsy.

Methods: A retrospective review of patients over a 6-year period was performed to determine patient outcomes and the patterns of recurrence. In all cases, Tc-99 sulfur colloid along with isosulfan blue dye was injected at the primary melanoma site. After resection, the SLN was serially sectioned and evaluated by hematoxylin and eosin staining and immunohistochemistry.

Results: One hundred ninety-eight patients were identified who underwent SLN biopsy for cutaneous melanoma including T1 (n = 21), T2 (n = 88), T3 (n = 75), and T4 (n = 14) primary tumors. Of these patients, 38 had a positive SLN. Of the 38 patients with a positive SLN (mean follow-up 38 months), recurrent disease was identified in 10 (26.3%) at a mean interval of 14.2 months. The site of first recurrence was distant (n = 4) and local (n = 6). Regional lymphatic basin recurrence was not identified. Of the 160 patients with a negative SLN (mean follow-up 50 months), recurrent disease was identified in 16 (10.0%) at a mean interval of 31.3 months. The site of first recurrence was systemic (n = 11), local (n = 4), and nodal (n = 1). Overall survival and disease-free survival for patients with a positive SLN at 55 months was 53.3% and 47.7% respectively, while overall survival and disease-free survival for patients with a negative SLN at 53 months was 92.2% and 87.7% respectively (P <0.01). Univariate and multivariate analysis of the entire cohort (n = 198) identified primary tumor depth and positive SLN status as significant predictors of recurrence.

Conclusions: The incidence of nodal basin recurrence after SLN biopsy was found to be 0.6%. Primary tumor depth and pathological status of the SLN are significant predictors of local and systemic recurrence. Long-term follow-up indicates that patients with a positive SLN clearly recur sooner and have decreased overall survival than those with a negative SLN.