Association of surgical margins with local recurrence in patients undergoing breast-conserving surgery after neoadjuvant chemotherapy

Background: The aim of the current study was to report a single-institution experience using breast-conserving surgery after neoadjuvant chemotherapy (NACT), focusing on the association between microscopic resection margin status and locoregional recurrence (LRR). Methods: Our institutional prospectively maintained database was reviewed to identify patients who were treated with NACT between January 2008 and April 2018. Results: Among the main partial mastectomy specimens available for analysis (n = 161), 28 had margins < 1 mm, 21 had margin width of 1-2 mm and the remaining 112 had margins > 2 mm. LRR occurred in 16 patients (9.9%) and distant metastases were detected in 27 (16.8%) patients. There was no significant difference in the LRR between the > 2 mm margin group with a 60-month cumulative survival of 85.2% compared with 76.2% for the ≤2 mm group (P = 0.335) in the Kaplan-Meier analysis. When we stratified patients by margin widths of ≥1 mm or < 1 mm, there was no LRR-free survival benefit observed for the ≥1 mm pathologic excision margin group in the univariate analysis (hazard ratio = 0.443; 95% confidence interval = 0.142-1.383; P = 0.161) with a 60-month cumulative LRR-free survival of 84.9% compared with 69.5% for the < 1 mm margin cohort (P = 0.150). Conclusions: In the absence of multiple scattered microscopic tumour foci, a negative margin of no ink on tumour maybe sufficient for stage I-III invasive breast cancer treated with NACT and breast-conserving surgery.