Lymph node tumor volumes in patients undergoing sentinel lymph node biopsyfor cutaneous melanoma

Background: Regional lymph node tumor volumes in patients undergoing sentin el lymph node (SN) biopsy (SNB) for treatment of cutaneous melanoma have no t been described. The objectives of this study were to describe the lymph n ode tumor volumes typically seen in this population and to correlate tumor volumes with tumor thickness and positive SN characteristics. Methods: Review of a consecutive series of patients with clinically localiz ed cutaneous melanoma who underwent SNB of nonpalpable regional lymph node basins followed by complete lymphadenectomy (LND) was performed. Multiple l ymph node sections from positive SNs and nonsentinel nodes (NSNs) in LND sp ecimens were examined microscopically. Individual tumor deposit diameters w ere measured using an ocular micrometer. Aggregate tumor volumes were calcu lated for SN and LND specimens. Tumor volumes and SN and LND positivity rat es were correlated with tumor thickness, the number of positive SNs, and th e presence of multiple SN tumor deposits. Results: SNB procedures were performed for 149 melanomas in 189 regional no dal basins. The mean tumor depth was 2.48 mm. The mean number of SNs/basin was 2.1. Thirty-two of 149 SNB procedures (21.5%) revealed a total of 34 no dal basins with at least one positive SN. The median tumor volume in positi ve SNs was 4.7 mm(3) (range, 0.1-3618 mm(3); mean, 209 mm(3)). The median a ggregate tumor volume in positive LND specimens was 4.9 mm(3) (range, 0.1-3 618 mm(3); mean, 224 mm(3)) Six basins (17.6%) contained at least one posit ive NSN. The regional node aggregate tumor mm volume correlated weakly with tumor thickness (Pearson's correlation coefficient = .302, P = .0934). NSN positivity was not predicted by tumor thickness, American Joint Committee on Cancer tumor stage, number of positive SNs, or number of metastatic depo sits within SNs, Conclusions: Most melanoma-positive SNs contain minute tumor volumes. Turne r thickness and patterns of SN metastases may not be predictive of tumor bu rden or the presence of positive NSNs.