Margins in Breast-Conserving Surgery After Neoadjuvant Therapy

Optimal margin width for breast-conserving therapy (BCT) after neoadjuvant chemotherapy (NAC) is unknown. We sought to determine the impact of margin width on local recurrence and survival after NAC and BCT.

Patients treated with NAC and BCT for stage I-III breast cancer from 2002 to 2014 were identified. Multivariate Cox regression was performed to determine the relationship between margin width and local recurrence free-survival (LRFS), disease-free survival (DFS), and overall survival (OS).

A total of 382 patients were included. Median age was 51 years [range 22-79], median tumor size 3.0 cm [range 0.6-11.0], and receptor subtypes included 144 (37.7%) HR-/HER2-, 47 (12.3%) HR-/HER2+, 118 (30.9%) HR+/HER2-, and 70 (18.3%) HR+/HER2+. Breast pathologic complete response (pCR) was achieved in 105 (27.5%) patients. Final margin status was positive in 8 (2.1%) patients, ≤ 1 mm in 65 (17.0%), 1.1-2 mm in 30 (7.9%), and > 2 mm in 174 (45.5%). The 5-year LRFS was 96.3% (95% CI 94.0-98.6), DFS was 85.5% (95% CI 81.8-90.7), and OS was 90.8% (95% CI 87.4-94.2). There was no difference in LRFS, DFS, or OS for margins ≤ 2 versus > 2 mm, and no difference in DFS or OS for margins ≤ 1 versus > 1 mm. HR+ subtype (p = 0.04) and pCR (p = 0.03) were correlated with favorable DFS and node negativity (p < 0.001) with favorable DFS and OS.

In this cohort treated with NAC and BCT, there was no association between margin width and LRFS, DFS, or OS. Although further studies are needed, the excellent long-term outcomes demonstrated in patients with close (≤ 2 mm) margins following NAC suggest that a margin of "no-ink-on-tumor" may be acceptable in appropriately selected patients.