Hormonal Receptor Positivity and Clinical Multifocality Are Independent Predisposing Factors for Positive Margin Events in Breast-Conserving Surgery after Neoadjuvant Chemotherapy

Abstract

Purpose: Neoadjuvant chemotherapy (NAC) frequently results in shrinkage of the primary tumor. It is not easy to perform breast-conserving surgery (BCS) after NAC, based on tumor extent alone. We identified the clinicopathological factors associated with positive margins on frozen or permanent sections in patients undergoing BCS after NAC. Methods: The records of 151 patients who had BCS after NAC between 2005 and 2010 were reviewed. All patients underwent subsequent imaging work-up including breast magnetic resonance imaging, ultrasound, and breast mammography at the midpoint and/or the end of NAC. Positive resection margins on frozen or permanent sections were considered to be due to the presence of either invasive carcinoma or in situ carcinoma. The relationship between the microscopic margin status and clinicopathological factors was analyzed when positive margins were detected. Results: Of 151 patients, 39 (25.8%) were diagnosed with a pathological complete response, while 135 patients (89.4%) had a negative margin on both frozen and permanent sections and 16 (10.6%) had a positive margin on frozen or permanent sections. Of the 16 patients, 14 finally obtained negative margins after additional excision and two (1.3%) had positive margins due to in situ carcinoma. Multivariate analysis revealed that clinical multifocality after NAC (p= 0.006), and hormonal receptor (HR) positivity (p= 0.028) were significantly associated with positive margins on frozen or permanent sections, but were not associated with tumor size after NAC, specimen volume, or human epidermal growth factor receptor 2 positivity. Conclusion: We propose that HR positivity and clinical multifocality after NAC are predisposing factors for positive margins in patients undergoing BCS after NAC. It is necessary to obtain safe resection margins to avoid positive margins in these patients.