Use of a Radiation Tumor Bed Boost Following Breast Conserving Surgery and Whole-Breast Irradiation: Time Trends and Correlates.

Abstract: Purpose We sought to evaluate time-trends and correlates of the use of a radiation tumor bed boost (TBB) following breast conserving-surgery (BCS) and either conventional or hypofractionated whole-breast irradiation (CWBI or HWBI) for patients with early-stage breast cancer. Methods and Materials The National Cancer Data Base was queried for patients diagnosed between 2012-2016. We evaluated the utilization of TBB prior to and after publication of the SSO-ASTRO margin guidelines in relation to sociodemographic variables, treatment facility, tumor characteristics, and whole-breast fractionation. Results The population included 380,387 patients, of whom 76.7% received a TBB. Utilization of a TBB decreased over time (2012-2013: 79.2%; 2014: 76.6%; 2015-2016: 74.7%; p 70, negative margins). Amongst patients undergoing HWBI, TBB was more frequently utilized when 15 fractions were used as compared to 16 fractions (76.8% vs. 59.1%, p Conclusion The use of a TBB decreased over time, coinciding with the publication of new margin guidelines for patients receiving CWBI and those with negative margins but increased for patients treated with HWBI. Hence, fractionation regimen is a critical variable in analyzing changes over time in the patterns of practice of details of breast irradiation.