Predictors of sentinel lymph node metastasis in melanoma

Several studies have examined the correlation between patient and tumour characteristics and sentinel lymph node (SLN) metastasis in patients with melanoma. Although most studies have identified Breslow thickness as an important factor, results for other variables have been conflicting. Much of this variability is probably because of differences in measurement techniques and reporting practices at different institutions. We sought to identify the predictors of SLN melanoma metastasis in our institution and patient population.

We performed a retrospective chart review of 348 patients with malignant melanoma who underwent SLN biopsy at a single institution from January 1999 to April 2007. We compared multiple variables related to patient demographics, primary tumour characteristics and SLN characteristics between patients in the positive and negative SLN groups.

Breslow thickness and nodular tumour type were independent factors significantly correlated with a positive SLN biopsy result in our study. Head and neck tumour location correlated with a lower likelihood of positive SLN status in univariate but not multivariate analyses.

This study confirms the status of Breslow thickness as a reproducible predictor of positive SLN status. We also found that nodular type was predictive of positive SLN status, an outcome that has not been reported by others.