Impact of Consensus Guidelines by the Society of Surgical Oncology and the American Society for Radiation Oncology on Margins for Breast-Conserving Surgery in Stages 1 and 2 Invasive Breast Cancer.

Abstract

This study aimed to evaluate the impact that the release of consensus guidelines for margins in breast-conserving surgery (BCS) had on re-excision rates. A retrospective review examined a prospectively maintained database of patients who had operable invasive breast cancer treated with BCS at the authors' institution. The patients were divided into two groups: (1) those with a diagnosis determined from 1 July 2011 to 31 July 2013 (before release of the guidelines) and (2) those with a diagnosis determined from 1 February 2014 to 31 July 2014 (after release of the guidelines). The groups were evaluated with respect to patient and tumor characteristics, re-excision rates, and reasons for re-excision. A total of 846 cases of BCS were managed: 597 in group 1 and 249 in group 2. Re-excision rates were significantly reduced after release of the consensus guidelines (p = 0.03). Re-excisions were performed for 115 (19 %) of 597 patients in group 1 and 32 (13 %) of 249 patients in group 2. After release of the guidelines, re-excisions were performed for positive margins, as defined by the consensus statement, in 25 (78 %) of 32 cases. The two groups did not differ significantly in terms of age, tumor size, grade, nodal status, estrogen receptor status, progesterone receptor status, or human epidermal growth factor receptor 2 status. Group 1 had more tumors of mixed ductal and lobular histology than group 2, and group 2 had more lobular tumors than group 1 (p = 0.02). The consensus guidelines on margins for BCS were applied for 78 % of the patients who underwent re-excision and resulted in a significant reduction in re-excision rates.