Prognostic importance of lymph node tumor burden in melanoma patients staged by sentinel node biopsy

Background: The objective of this study was to investigate the relationship between nodal tumor burden and the outcomes of recurrence and survival in sentinel node-positive melanoma patients. Methods: We reviewed a series of sentinel node-positive patients with primary cutaneous melanoma treated with completion lymph node dissection (CLND). Microscopic nodal tumor deposits were counted and measured with an ocular micrometer. Various measures of tumor burden and traditional melanoma prognostic indicators were studied in multivariate Cox regression models. Results: Sentinel lymph node and CLND specimens were evaluated in 90 node-positive patients. The diameter of the largest lymph node tumor nodule and the total lymph node tumor volume were significant predictors of recurrence (two-sided P < .0001 for both) and survival (two-sided P = .0018 and P = .0002, respectively). A tumor deposit diameter of 3 mm was identified as the most significant cut point predictive of recurrence (P < .0001; hazard ratio, 5.18) and survival (P < .0001; hazard ratio, 5.43). The 3-year survival probability was .86 for patients with largest tumor deposit diameters of : 3 mm and was .27 for patients with largest deposit diameters >3 mm (P < .0001). Conclusions: Microstaging of melanoma sentinel lymph node/CLND specimens by using the diameter of the largest tumor deposit is a highly significant predictor of early relapse and survival.