5 years of experience with DIBH (Deep inspiration breath-hold) combined with SGRT (Surface-Guided Radiation Therapy) in left-sided breast cancer

Background Radiation treatment to the left breast is associated with increased cardiac morbidity as well as mortality. Deep inspiration breath-hold (DIBH) technique with Surface Guided Radiation Therapy (SGRT) could have dosimetric advantages over the free breathing technique (NB, normal breathing) in cardiac (heart and LAD) and ipsilateral lung sparing in patients with left-sided breast cancer after surgery. Therefore this technique was implemented in 2013 at the institute of radiooncology at the KFJ/SMZ-South – Hospital Vienna. Methods From Oct 2013 – December 2018 548 patients were referred to radiotherapy following conservative operation of left-sided invasive breast cancer. All patients gave their informed consent and underwent training sessions for the DIBH-technique independent of age or breathing activity or respiratory disorders. Patients who turned out to be unfit for DIBH were enrolled for NB. The relative reduction in Dmean heart and left lung dose was compared between the two cohorts. Acute radiation induced side effects were classified according to the Radiation Therapy Oncology Group/The European Organisation for Research (RTOG) 37 ; late toxicity rates according to the Common Terminology Criteria for Adverse Events (CTCAE Version 4.03) Results The median age of the DIBH-patients was 58 years (27–90), of the NB-patients 65 (30–80) years. Follow-up was obtained until June 2019. The median follow-up was 52 months (range 7–73 m). The average coverage of Dmean left lung was 6.91 Gy (1.44 Gy – 12.4 Gy). The average coverage of Dmean heart was 1.17 Gy (0.12 Gy – 3.19 Gy) in the DIBH-cohort. The NB – plans had a Dmean of 8.92 Gy (5.23–16.9 Gy) at the ipsilateral lung and a Dmean of 2.31 Gy (0.71–4.21 Gy) at the heart. This shows that the DIBH-technique halved the Dmean of the heart. The amount of acute side effects was comparable between the two groups: RTOG 1: 70.8 % vs. 64 %, RTOG 3 6.6 % vs. 5.6 %, no reaction 3.2 % vs. 1.4 %. There were more CTCAE 1-late events in the NB-group (51.6 % vs. 12.67 %). Conclusion Deep inspiration breath-hold (DIBH) technique with Surface Guided Radiation Therapy (SGRT) is a rather simple, reproducable method with a high acceptance of the patients who can actively participate in the whole treatment process. The mean dose at the heart and the left lung can be reduced, at the heart even by as much as 50 %.