Intra-Operative Gross Margin Evaluation in Breast Conservation Surgery: Assessing the Minimum Adequate Gross Margin Required to Achieve Microscopic Tumor-Free Margins

Abstract

The aim of a breast conservation surgery (BCS) is to achieve complete excision of the tumor with clear surgical margins while preserving the normal breast as much as possible. Intra-operative margin assessment helps to achieve negative margins, decreasing the need for re-excision. Intra-operative gross margin evaluation is a cost-effective and easy technique; however, data available regarding its adequacy are limited. We aim to find the minimum adequate gross margin required to achieve microscopic tumor-free margins and assess the relation if any of margin status with the tumor type, grade, nodal status and immunohistochemical (IHC) markers. A total of 178 patients who underwent BCS from the years 2013–2018 in our tertiary care center were selected, excluding the ones who underwent prior neoadjuvant chemotherapy and excision biopsy. A retrospective chart review was done, and the minimum adequate cutoff of gross margins required to achieve negative margins, without any positive or close margins, was evaluated. Ten exceptional cases were excluded. Among the 168 cases, 147 (87.5%) had negative and 21 (12.5%) had close or positive margins. On evaluation, maintaining an average gross margin of 5.5 mm gave a positive predictive value of 95.45%. The sensitivity and specificity were 71.43% and 76.19%, respectively, with an accuracy of 72%. No correlation was obtained between gross margin status and tumor characteristics. Gross margin evaluation is a fast and cost-effective method which can be easily set up in any hospital setting with limited resources to ensure negative margins during BCS.