Impact of Cavity Shaving on Margin Status and Re-excision Rates in Breast-Conserving Surgery: Experience from a Single Institute.

BACKGROUND: The comparative outcomes of breast-conserving surgery (BCS) with and without cavity shave margins (CSM) are not well established, despite prior randomized and observational studies, due to heterogeneity in patient populations and margin definitions. We aim to evaluate the impact of each procedure on final margin status and subsequent re-excision rates. METHODS: We conducted a retrospective study comprising 529 women who underwent either BCS with CSM or BCS without CSM between 2013 and 2015 for ductal carcinoma in situ (DCIS), invasive ductal carcinoma (IDC), or both at Detroit Medical Center, Michigan. Data, including final margin status (inked and close margin) and re-excision status, were collected. Statistical analysis was performed using univariable and multivariable logistic regression analyses. RESULTS: Our analysis revealed no significant reduction in the incidence of positive margins (involved and tumor within 2 mm) among patients who underwent either procedure. In the univariable analysis, patients without lymph node (LN) metastases, those who underwent BCS with CSM, and those with pure IDC had a decreased risk of re-excision compared with those without LN sampling and those with only DCIS (all P < 0.001), respectively. These factors also remained significant in multivariable analysis. CONCLUSION: Although no significant difference was observed between the 2 procedures in reducing the incidence of positive margins among patients with only IDC, only DCIS, and both IDC and DCIS, CSM showed a lower need for re-excision, particularly in cases with pure IDC.