Impact of SSO-ASTRO "No Ink on Tumor" Guidelines on Reexcision Rates among Older Breast Cancer Patients.

BACKGROUND: The SSO-ASTRO consensus guideline on invasive breast cancer defined negative margin as no ink on tumor, obviating the need for reexcision in some patients. We evaluated the impact of these recommendations on the rates of reexcision in older breast cancer patients undergoing breast-conserving surgery (BCS). PATIENTS AND METHODS: Women age ≥ 66 years with stage I-II breast cancer who underwent BCS and radiation were identified in the SEER-Medicare linked database (2012-2015). We divided patients into three cohorts: pre-guideline (January 2012 to September 2013), peri-guideline (October 2013 to March 2014), and post-guideline (April 2014 to September 2016). Descriptive statistics were used, and the relative change in reexcision rate between the pre- and post-guideline periods was calculated. Multivariable logistic regression was used to evaluate factors associated with risk of reexcision. RESULTS: A total of 11,639 patients were included (pre-guideline, N = 5211; peri-guideline, N = 1366; post-guideline, N = 5062); overall, 21.7% of patients underwent reexcision. The reexcision rates decreased after the guideline was published (23.5% vs. 19.3%, p < 0.001). In the multivariable model, BCS during the post-guideline period was associated with a statistically significant decreased risk of reexcision (RR = 0.84; 95% CI 0.78-0.90). Lobular histology was associated with a higher risk of reexcision (RR = 1.32; 95% CI 1.19-1.46), and greater surgeon volume was associated with lower risk of reexcision (RR = 0.92; 95% CI 0.85-1.0). CONCLUSIONS: Among older breast cancer patients undergoing BCS for invasive cancer, reexcision rates decreased with the dissemination of the SSO-ASTRO consensus guideline. Identifying factors associated with higher rates of reexcision could improve guideline compliance and reduce the frequency of unnecessary interventions in older patients.