The SSO/ASTRO Consensus on Breast Margins: Has it affected clinical practice?

Abstract

148 Background: Adequate margin width remains a subject of much controversy in breast conserving surgery. The Society of Surgical Oncology (SSO) and the American Society for Radiation Oncology (ASTRO) presented a consensus statement on margins in December 2014. This guideline stated that re-excision is recommended only in cases where tumor is present on inked margin. In this study, we sought to determine the consensus statement’s impact on re-excision practices at our institution. We examined re-excision rates eleven months before the release and 17 months after the release of the statement. Methods: Patients included in this IRB approved study had a diagnosis of invasive breast carcinoma, underwent breast conserving surgery, and were treated with adjuvant radiotherapy. Patients with pure DCIS were excluded. Results: One hundred and two women treated from January to November 2013 were included in the pre-consensus group. One hundred and three women were treated from December 2013 to May 2015 in the post-consensus group. The women treated prior to the consensus statement (n = 102) and those women treated after the statement (n = 103) were equally matched in terms of patient age, hormone positivity, and tumor size. A close margin at our institution is defined as < 2mm from the tumor edge. There were 16/102 women prior to the consensus who had close margins and 32/103 women in the post-consensus group. Of these, 68.8% (11/16) underwent re-excision for close margins in the pre-consensus group compared to 3.1% (1/32) after the consensus statement was released (p value < 0.01). Conclusions: The rapid adoption of the SSO/ASTRO margin consensus statement at our institution, although not statistically significant, led to a decrease in the number of patients who underwent a re-excision for close margins. Women with a close surgical margin were less likely to undergo additional surgery for re-excision after the guidelines were released. In our institution, using a standard criterion for re-excision, the re-excision rate for close margins decreased from 68.8% to 3.1%. Further studies are needed to examine the impact of the consensus statement on re-excision practices in a larger group of patients.