Revised American Joint Committee on Cancer staging criteria accurately predict sentinel lymph node positivity in clinically node-negative melanoma patients

Background: The American Joint Committee on Cancer (AJCC) has recently modified staging criteria for primary melanoma patients and recommends sentinel lymph node (SLN) biopsy in many because microscopic nodal metastasis represents the most important factor predicting survival. The purpose of this study was to correlate the incidence of SLN metastasis with revised AJCC staging. Methods: The records of 1375 melanoma patients undergoing SLN biopsy were reviewed. Univariate and multivariate analyses were performed to identify predictors of a positive SLN. Patients were stratified by using revised AJCC criteria to determine whether such groups also predicted positive SLNs. Results: A positive SLN was found in 16.9% of patients. By multivariate analysis, tumor thickness (relative risk [RR], 3.4) and ulceration (RR, 2.2) were dominant independent predictors of SLN metastases; age ≤50 years (RR, 1.8) and axial tumor location (RR, 1.5) were also significant. When patients were stratified by AJCC staging criteria, a significant increase in SLN metastases between successive stages was demonstrated. Conclusions: Stratification of patients by using AJCC classification reveals an increasing risk of SLN metastases with successive stage groups. Given the significant association of SLN status and survival, the ability of the revised AJCC staging system to predict survival is likely due to its ability to predict the risk of occult nodal disease.