ESTRO 2022 - Abstract Book

S1018

Abstract book

ESTRO 2022

Conclusion Partial breast reirradiation for local breast cancer with external beam radiotherapy is well tolerated with a low rate of severe acute toxicity. Mature follow-up is needed to adequately characterize the late toxicity. Local control with this approach is excellent.

PO-1196 Deep Inspiration Breath Hold in Left Sided Whole Breast Radiotherapy: a single-center experience

F. MAURIZI 1 , F. Palleri 2 , M. Mazza 1 , A. Ciarmatori 2 , C. Blasi 1 , E. Argazzi 2 , G. Capezzali 1 , M. La Macchia 1 , G.L. Moroni 1 , S. Giancaterino 2 , M.B.L. Rocchi 3 , M. Bono 2 , F. Bunkheila 1 1 Radiation Oncology Unit, Az. Osp. Ospedali Riuniti Marche Nord, Pesaro, Italy; 2 Medical Physics and Health Technology Unit, Az. Osp. Ospedali Riuniti Marche Nord, Pesaro, Italy; 3 Department of Biomolecular Sciences, University of Urbino Carlo Bo, Urbino, Italy Purpose or Objective After breast conserving surgery, adjuvant radiotherapy (RT) to the conserved breast reduces the risk of recurrence and improves overall survival. In previous studies, late cardiac toxicity appeared to be a rare but relevant sequelae related to unavoidable irradiation to the heart during left sided radiation treatments. The aim of this analysis is the evaluation of the benefits of Deep Inspiration Breath-Hold (DIBH) technique compared with Free Breathing (FB) in the treatment of breast cancer patients (pts). Materials and Methods The patient selection included women undergoing whole breast radiotherapy (WBRT) after lumpectomy for left sided breast cancer. The respiratory gating systems were optical surface scanning devices: Sentinel for the CT simulation and Catalyst HD for the radiation treatment. Respiratory signal has been monitored in the lower part of the sternum at the height of the xiphoideus process. The chosen gating window was between 3-5 mm. The patient training was carried out with electronic eyeglasses (video coaching). Only patients able to follow the training to find their individual deep inspiration level and to retain breathing for at least 20 seconds have been included. Patients underwent the planning CT in the supine position with the acquisition of both Free Breathing (FB) and DIBH image sets. Contouring and treatment planning were realized on both CT studies with Monaco TPS. From March 2019 to September 2021, 97 patients (median age: 53 years, range: 24-75) successfully completed DIBH simulations. Eighty-six patients were treated with 40 Gy in 15 fractions (fr) and 11 pts with 50 Gy in 25 fr. The following dosimetric parameters were evaluated and compared for statistically significant differences using the Mann-Whitney Test in both FB and DIBH plans: mean heart dose (MHD), D2cc and V13, left mean lung dose (MLD) and V18 in hypofractionation or V20 in conventional treatments. Results Seventeen plans were realized with VMAT modality and 80 with 3DCRT planning technique. All cardiac dosimetric parameters were significantly improved with the use of DIBH: MHD and D2cc decreased of 33% (1.61 Gy FB vs 1.09 Gy DIBH; p<0.0001) and 56% (17.72 Gy FB vs 7.76 Gy DIBH; p<0.0001) respectively. For left MLD the average dose reduction was 6% with DIBH (p=0.04). Patients treated with VMAT modality experienced a significantly larger reduction in MLD (10.5%). The difference in Lung V18 (or V20) was not statistically significant. Conclusion DIBH with surface tracking systems results to be a feasible and effective option for cardiac dose sparing. This benefit could potentially reduce long term major coronary events. Clinical correlations are expected.