Additional Cavity Shaving at the Time of Breast-Conserving Surgery Enhances Accuracy of Margin Status Examination.

Abstract

We addressed the impact of separate cavity margin excision (shaving) during breast-conserving surgery (BCS) for breast cancer on specimen volume, tumor margin clearance, re-excision rate, local recurrence and survival. A retrospective case-matched study was performed on 298 women with stage 0-III breast cancer; 179 patients received shaving (shaving+lumpectomy group; SLG) and 119 patients did not (lumpectomy group; LG). The two groups had similar baseline characteristics. The median volume of surgical specimen was 131.9cc in the SLG versus 134.8cc in the LG (p=0.81), and surgical margins were tumor-free in 90.7% of cases in the LG versus 92.7% in the SLG (87.1% before shaving) (p=0.69). The re-excision rate was 14.3% in the LG versus 10.6% in the SLG (p=0.44). In the SLG, shaving spared 10 (5.6%) patients from reoperation (positive lumpectomy margins but tumor-free shaving margins) (p=0.11), and only 2/19 (10.5%) patients in the SLG had tumor-free response at histological examination of re-excised margins compared with 10/17 (58.8%) cases in the LG (p=0.004). Tumor in shavings was found in 44/156 (28.2%) patients having tumor-free lumpectomy margins. At multivariate analysis, distance of tumor from lumpectomy margins, tumor multifocality, receptor status, and tumor size were related to tumor persistence in shavings. Median follow-up was 27months (range 23-35), and two patients had tumor relapse in the SLG versus none in the LG (p=0.16). Overall survival was 100% in both groups. Shaving does not significantly decrease the re-excision rate but provides wider clear margins in most procedures. It ensures more accurate margin examination and decreases false-positive margin rate, without any increase in removed breast-tissue volume.