Recurrence Rate Following Breast Conservation Surgery: A Retrospective Cohort Study

Breast-conserving surgery (BCS) has become the standard treatment for early-stage breast cancer, offering oncological safety, better breast aesthetics, and enhanced health-related quality of life. The optimal margins for BCS have been debated. However, evidence on the impact of margin widths greater than 0 mm for invasive breast cancer remains limited. Cambridge Breast Unit (CBU) has adopted a policy where a single margin of < 1 mm (not at ink) for invasive disease would be acceptable, provided the other three radial margins are ≥ 1 mm.

Retrospective cohort study analyzed 372 women who underwent BCS for invasive breast cancer at CBU between 2015 and 2016. Patients with pure ductal carcinoma in situ (DCIS), prior breast cancer treatment, or neoadjuvant chemotherapy were excluded. Clinical data, including patient demographics, tumor characteristics, margin status, and recurrence and survival outcomes, were extracted from electronic records.

At a median follow-up of 5.2 years, the ipsilateral breast tumor recurrence (IBTR) rate was 1.6% (6/372) with an overall recurrence rate of 5.6% (21/372). No significant association was found between final resection margins and local or overall recurrence rates, nor was margin status correlated with breast cancer recurrence-free survival. A total of 53 patients (14.2%) required additional surgeries due to margin status. By accepting a single radial margin < 1 mm, our margin policy reduced reoperations by 33%.

Margin assessment in breast surgery is multifaceted, requiring a personalized approach that considers tumor biology, systemic treatments, and pathological variability. Our findings support accepting a margin width of < 1 mm (no tumor on ink) for a single radial margin in invasive breast cancer, provided the other three radial margins are ≥ 1 mm. It reduces reoperations without compromising oncological outcomes. Integrating advanced intraoperative techniques and multidisciplinary decision-making will further optimize patient care and long-term outcomes.