The Importance of Adequate Primary Tumor Excision Margins and Sentinel Node Biopsy in Achieving Optimal Locoregional Control for Patients With Thick Primary Melanomas

Abstract

This study sought to investigate the impact of histopathologically measured excision margins and SNB on local and locoregional disease control in patients with primary cutaneous melanomas more than 4 mm thick. Most current guidelines recommend at least a 2-cm surgical margin (which corresponds to a 16-mm histopathologic margin). These guidelines are based on limited evidence, mostly obtained in patients who did not have an SNB. Histopathologic tumor excision margins for clinically lymph node-negative patients with melanomas more than 4 mm thick, treated at Melanoma Institute Australia (1992-2009), were determined. Clinicopathologic predictors of local and locoregional disease-free survival were investigated. There were 632 patients eligible for the study; of these, 397 (62.8%) had an SNB. The median histopathologic excision margin was 15 mm (interquartile range, 11.0-19.5 mm). After a median follow-up of 37 months, local and locoregional recurrences were observed in 48 (7.6%) and 159 (25.2%) patients, respectively. Excision margin as a continuous variable was a significant predictor of local [hazard ratio (HR), 0.91; P < 0.001) and locoregional (HR, 0.97; P = 0.042) tumor control on multivariate analyses. Patients with histopathologic margins 16 mm or less had worse local disease-free survival (HR, 2.41; P = 0.01). Patients who did not have an SNB were at higher risk of locoregional recurrence (HR, 1.67; P = 0.003). Histopathologically determined primary tumor excision margins more than 16 mm, corresponding to 2-cm surgical margins, were associated with better local control in patients with melanomas more than 4 mm thick. Patients achieved the best local and locoregional control when SNB was coupled with a more than 16-mm histologic excision margin.