Role of re-excision for positive and close resection margins in patients treated with breast-conserving surgery

PURPOSE: To evaluate the incidence of residual disease after additional surgery for positive/close margins and the impact on the rate of local and distant recurrence. METHODS: A retrospective analysis on 1339 patients treated for breast cancer with breast conserving-surgery and radiotherapy at a single Institution between 2000 and 2009 was performed. RESULTS: During primary surgery 526 patients (39.3%) underwent intraoperative re-excision. At the final pathological report, the margins were positive in 132 patients (9.9%) and close in 85 (6.3%). To obtain clear margins, 142 of these women underwent a second surgery; 35 patients with positive margins (27%) and 40 with close margins (47%) did not receive additional surgery because of different reasons (patients refusal, old age, comorbidity or for focal margin involvement). At second surgery, residual disease was found in 62.9% of patients with positive margins and in 55.5% of those with close margins. At a median follow-up time of 4 years, local recurrence (LR) rate was 2.9% for patients with clear margins, 5.2% (p = 0.67) for patients with unresected close margins and 11.7% (p = 0.003) for those with unresected positive margins. The HER-2 and the basal-like subtypes had the higher rate of LR and the luminal A the lowest. CONCLUSIONS: A significantly higher LR rate was found only among patients with positive margins not receiving additional surgery, but not in those with unresected close margins. Positive margins are a strong predictor for LR and need re-excision that can be avoided for close margins.