ESTRO 2023 - Abstract Book

S1772

Digital Posters

ESTRO 2023

PO-1999 HEART AND LUNG COMPLICATION PROBABILITY IN LEFT BREAST CANCER: COMPARISON BETWEEN FB AND DIBH RT M. Caroprese 1 , A. Barillaro 2 , C. Oliviero 3 , L. Cella 4 , C. Feoli 3 , C. Mainardi 3 , S. Clemente 3 , S. Coppola 3 , E. Chioccola 3 , M. Conson 3 , R. Pacelli 5 1 University of Naples Federico II , Department of Advanced Biomedical Sciences, Naples, Italy; 2 University of Naples Federico II , Department of Advanced Biomedical Sciences , Naples, Italy; 3 University of Naples Federico II, Department of Advanced Biomedical Sciences , Naples, Italy; 4 Institute of Biostructures and Bioimaging, National Research Council, Naples, Italy; 5 University of Naples Federico II, Department of Advanced Biomedical Sciences, Naples, Italy Purpose or Objective Deep inspiratory breath-hold (DIBH) has become standard in radiotherapy for left-sided breast cancer to reduce the heart dose. The aim of this study is to compare normal tissue complication probability (NTCP) between DIBH and free breathing (FB) techniques and to evaluate the potential dosimetric benefit of DIBH at the cardiac substructure level. Materials and Methods One hundred and sixteen patients with left-sided breast cancer who received whole-breast irradiation were included. Cardiac chambers and coronary arteries were delineated according to ESTRO guidelines. The plans were simulated in FB and DIBH CT scan for each patient to be equivalent for target coverage, namely 95% prescription dose (40 Gy in 15 fractions on whole breast plus 10 Gy in four fractions on tumor bed when appropriate) to 95% of target volume. Dosimetric parameters for all cardiac substructures were retrieved and compared between both simulation plans. Five Lyman Kutcher Burman (LKB) models were applied to evaluate cardiac perfusion defects (Das et al., 2005), long-term cardiac mortality (Gagliardi et al., 1996), coronary stenosis (Moignier et al., 2015), pericardial effusions (Martel et al., 1998), and radiation-induced pneumonitis (Rancati et al., 2007) in both techniques. Results Whole heart and coronary arteries doses were significantly reduced in DIBH plans considering all dosimetric parameters. In particular, the heart mean dose (Dmean) and the heart maximum dose (Dmax) were reduced in DIBH approach by 37% and 58% respectively. All cardiac chambers reported a significative dose reduction of Dmean and near-maximum D2. The NTCP application showed a significative reduction considering perfusion defects, coronary stenosis, pericardial effusions, and radiation-induced pneumonitis in DIBH plans. Only for long-term cardiac mortality was not found a significative reduction in DIBH plans (p=0.301). Conclusion The dosimetric benefit of DIBH over FB therapy was consistently observed for all cardiac substructures. The DIBH technique promises a significant advantage in ameliorating the heart toxicity profile of left breast irradiation.