Dosimetric Efficacy of Voluntary Deep Inspiration Breath-Hold in the Radiotherapy of Left Breast Cancer Patients Using the UK START Trial

Introduction: Deep inspiration breath-hold (DIBH) technique is widely administered to left breast cancer (LBC) patients to reduce the cardiopulmonary radiation doses. The UK standardization of breast cancer radiotherapy (UK START) dose prescription was found comparable to the conventional schedule. The current study compared voluntary DIBH and free-breathing (FB) methods in the cardiopulmonary radiation doses of LBC patients with supraclavicular irradiation treated with the UK START trial. Material and Methods: Computed tomography (CT) scans were acquired for a group of 50 LBC patients in DIBH and FB and a radiotherapy plan was created on each scan. The dose-volume histogram parameters of the heart and lung were analyzed against their relevant first clinical acceptance criteria using one-sample t-test. Additionally, the correlation between the ipsilateral lung volume expansion and the cardiopulmonary dosimetric benefits was assessed. Results: The cardiopulmonary radiation doses were significantly reduced in DIBH compared with FB. For DIBH, the mean difference between the mean heart dose (MHD), Heart V16Gy, and Lung V16Gy and their first acceptance criteria was -62.6 cGy, -0.63%, and -2.18% (p < 0.001), respectively. In contrast, the first acceptance criteria of the cardiopulmonary dosimetric parameters were not accomplished with the FB method. In addition, the difference in MHD and heart V20Gy between DIBH and FB plans showed a moderate correlation with ipsilateral lung volume expansion (r = 0.51 and 0.5, respectively). Conclusion: DIBH technique should be served to all locally advanced LBC patients, and the ipsilateral lung volume expansion could be a predictor for the cardiac-sparing radiotherapy in LBC.