Improved heart, lung and target dose with deep inspiration breath hold in a large clinical series of breast cancer patients

Background and purpose: This study aims at evaluating the effect of deep-inspiration breath hold (DIBH) on target coverage and dose to organs at risk in a large series of breast cancer patients. Materials and methods: Clinical dose plans for 319 breast cancer patients were evaluated: 144 left-sided patients treated with DIBH and 175 free-breathing (FB) patients (83 left-sided and 92 right-sided). All patients received whole breast irradiation with tangential fields, based on a forward-planned intensity-modulated radiation therapy (IMRT) technique. Dose to heart, ipsi-lateral lung and ipsi-lateral breast were assessed and median values compared between patient groups. Results: Comparing group median values, DIBH plans show large reductions of dose to the heart compared with left-sided FB plans; V _20Gy (relative volume receiving ≥20 Gy) for the heart is reduced from 7.8% to 2.3% (-70%, p < 0.0001), V _40Gy from 3.4% to 0.3% (-91%, p < 0.0001) and mean dose from 5.2 to 2.7 Gy (-48%, p < 0.0001). Lung dose also shows a small reduction in V _20Gy (p < 0.04), while median target coverage is slightly improved (p = 0.0002). Conclusions: In a large series of clinical patients we find that implementation of DIBH in daily clinical practice results in reduced irradiation of heart and lung, without compromising target coverage.