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

Purpose: 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.

Methods: 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).

Results: The two groups had similar baseline characteristics. The median volume of surgical specimen was 131.9 cc in the SLG versus 134.8 cc 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 27 months (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.

Conclusions: 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.