The impact of preoperative magnetic resonance imaging and lumpectomy cavity shavings on re‐excision rate in pure ductal carcinoma in situ—A single institution's experience

BACKGROUND AND OBJECTIVES: The impact of preoperative magnetic resonance imaging (pMRI) and cavity shave margins (CSM) on re-excision rate (RR) in DCIS is unclear. We investigated whether either modality was associated with RR in DCIS. METHODS: This is a single-institution retrospective study of 295 women undergoing breast conservation surgery for pure DCIS (2010-2013). CSM were the systematic resection of 4-6 margins during lumpectomy whereas selective shave margins (SSM) were the selective resection of 1-3 margins. Patient demographics and clinical characteristics were abstracted. RR was analyzed according to the use of pMRI, SSM, or CSM with respect to three high-volume breast surgeons at our institution. RESULTS: RR was not associated with the use of pMRI (P = 0.87). Any shave margins (P = 0.05), DCIS size (P < 0.001), and DCIS grade (P = 0.14) associated with a lower RR. Of our high-volume surgeons, RR was lower for Surgeon A (P = 0.02). Multivariate analyses showed larger DCIS (OR 1.35, P = 0.005) and practices specific to surgeons B (OR 3.23, P = 0.04) and C (OR 3.57, P = 0.04) increased re-excision odds. CONCLUSIONS: SSM/CSM and pMRI use varied among surgeons. Our results suggested the routine use of CSM, not pMRI, could lower re-excision rate, which highlighted a quality improvement opportunity at our institution.