Intraoperative Margin Assessment in Wire-Localized Breast-Conserving Surgery for Invasive Cancer: A Population-Level Comparison of Techniques.

Abstract

Various intraoperative margin assessment techniques have been shown to improve margin status in breast-conserving surgery (BCS) for cancer. Our study sought to evaluate multiple margin assessment techniques on a population level and determine their effects on margin status. Patients undergoing wire-localized BCS for invasive cancer in Alberta, Canada, were assessed using a prospectively entered database of patient and tumor characteristics. Margin status was obtained from chart review. Four margin assessment techniques were studied: specimen mammography (SM), intraoperative ultrasound (US), gross assessment by pathologist (GP), and frozen section analysis (FS). Multivariable logistic regression adjusting for confounders was used to assess effect of any technique on margin status, with secondary analysis evaluating effects of individual techniques. Margin assessment was performed in 1165 of 1649 patients (71%). The overall positive margin rate was 20.8%. Adjusting for confounders, we found no difference in the odds of a positive margin with any margin assessment technique versus wire localization alone (OR 0.79, p=0.22, 95% CI 0.54-1.16). Individually, both GP and FS reduced the risk of a positive margin (GP-OR 0.56, p=0.002, 95% CI 0.39-0.81; FS-OR 0.43, p=0.046, 95% CI 0.19-0.98), whereas SM and US showed no effect (SM-OR 1.23, p=0.29, 95% CI 0.84-1.81; US-OR 1.09, p=0.83, 95% CI 0.50-2.37). Use of any margin assessment technique did not improve margin status compared to wire localization alone. Gross assessment by pathologist and frozen section analysis improved margin status compared to imaging-alone techniques. Further exploration is required to refine optimal margin assessment methods.