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

Abstract

We sought to evaluate time trends and correlates of the use of a radiation tumor bed boost (TBB) after breast-conserving surgery and either conventional or hypofractionated whole-breast irradiation (CWBI or HWBI) for patients with early stage breast cancer. The National Cancer Database was queried for patients diagnosed between 2012 and 2016. We evaluated the utilization of TBB before and after publication of the Society of Surgical Oncology-American Society for Radiation Oncology margin guidelines in relation to sociodemographic variables, treatment facility, tumor characteristics, and whole-breast fractionation. The population included 380,387 patients, of whom 76.7% received a TBB. Utilization of TBB decreased over time (2012-2013: 79.2%; 2014: 76.6%; 2015-2016: 74.7%; P < .001); this was seen for most subgroups evaluated. Rates of TBB differed by facility type and region. There was a decrease in TBB use in patients treated with CWBI over time (2012-2013: 84.9%; 2014: 83.5%; 2015-2016: 82.3%; P < .001) but an increase among patients treated with HWBI (2012-2013: 55.5%; 2014: 60.7%; 2015-2016: 65.1%; P < .001); this was also seen for low-risk patients (age >70 years, negative margins). Among patients undergoing HWBI, TBB was more frequently used when 15 fractions were used compared with 16 fractions (76.8% vs 59.1%; P < .001). The use of TBB decreased over time, coinciding with the publication of new margin guidelines, for patients receiving CWBI and those with negative margins, but TBB use increased for patients treated with HWBI. Hence, fractionation regimen is a critical variable in analyzing changes over time in the practice patterns of TBB.