Lower mean heart dose with deep inspiration breath hold-whole breast irradiation compared with brachytherapy-based accelerated partial breast irradiation for women with left-sided tumors

For women with left-sided early-stage breast cancer, DIBH-WBI resulted in statistically significantly lower mean BED to the heart and coronary vessels compared with APBI. This is likely due to increased physical separation between the heart and tumor bed afforded by the DIBH-WBI technique. Long-term assessment of late effects in these tissues will be required to determine whether these differences are clinically significant.