Does intra-operative margin assessment improve margin status and re-excision rates? A population-based analysis of outcomes in breast-conserving surgery for ductal carcinoma in situ.

Despite adherence to a 2 mm margin criteria, re-excision rates remain high following BCS for DCIS, with 39% converted to mastectomy when re-excision is required. Intra-operative margin assessment does not appear to reduce re-excisions; in particular, surgeons should be aware of the limitations of specimen mammography for margin assessment in DCIS.