Recent Time Trends and Predictors of Heart Dose From Breast Radiation Therapy in a Large Quality Consortium of Radiation Oncology Practices

PURPOSE: Limited data exist regarding the range of heart doses received in routine practice with radiation therapy (RT) for breast cancer in the United States today and the potential effect of the continual assessment of the cardiac dose on practice patterns. METHODS AND MATERIALS: From 2012 to 2015, 4688 patients with breast cancer treated with whole breast RT at 20 sites participating in a state-wide consortium were enrolled into a registry. The importance of limiting the cardiac dose has been emphasized in the consortium since 2012, and the mean heart dose (MHD) has been reported by each institution since 2014. The effects on the MHD were estimated for both conventional and accelerated fractionation using regression models, with technique (intensity modulated RT [IMRT] vs 3-dimensional conformal RT), deep inspiration breath hold use, patient position (supine vs prone), nodal RT (if delivered), and boost (yes vs no) as covariates. RESULTS: For left-sided breast cancer treated with conventional fractionation, the median MHD in 2012 was 2.19 Gy versus 1.65 Gy in 2015 (P CONCLUSIONS: The MHD for left-sided breast cancer decreased during a recent 4-year period, coincident with an increased focus on cardiac sparing in the radiation oncology community in general and a state-wide consortium specifically. These data suggest a positive effect of systematically monitoring the heart dose delivered