Completion lymph node dissection (CLND) for melanoma after positive sentinel lymph node biopsy (SLNB) was recently shown to improve regional but not overall survival, likely due to the majority of patients harboring no further nodal disease. We sought to determine predictors of non-sentinel node (NSN) positivity.

Retrospective review of prospectively collected data on melanoma patients undergoing SLNB.

116 patients underwent 119 CLNDs. The incidence of NSN positivity was 17.6%; the average number of positive NSNs in those cases was 1.5. Cervical and inguinofemoral location were most likely to yield positive NSN(s) (40% each). Conversely, the axilla was least likely at 18% (p < 0.001). The average number of nodes harvested was 13 for NSN negative cases and 20 for NSN positive cases (p = 0.005). Tumor thickness increased the probability of positive NSN(s) (OR 1.2, p = 0.02).

Tumor thickness and nodal basin were predictors of NSN metastasis, factors that could help determine which patients may benefit from CLND. Further, CLNDs with fewer nodes may inadequately clear residual nodal disease.