Size of sentinel node metastases predicts other nodal disease and survival in malignant melanoma

BackgroundA positive sentinel lymph node (SLN) biopsy is an indication for completion lymph node dissection (CLND) in malignant melanoma; however, most CLNDs are negative. We hypothesized SLN metastatic size of ≤2 mm would predict CLND status and prognosis.MethodsWe evaluated 80 consecutive patients undergoing CLND for positive SLNs over a 10-year period. Incidence of positive nonsentinel nodes and survival were compared for patients with SLN metastases ≤2 mm and >2 mm.ResultsOf 504 patients undergoing SLN biopsy, 49 patients had SLN deposits ≤2 mm and a 6% incidence of positive CLNDs. Five-year survival was 85%, essentially the same as negative SLN biopsies. In contrast, 31 had SLN metastases >2 mm, a 45% incidence of addition disease at CLND, and 5-year survival of 47% (P < .0001).ConclusionAn SLN metastatic cut point of 2 mm is an efficient predictor of CLND status and survival in malignant melanoma.