ESTRO 2024 - Abstract Book

S656

Clinical - Breast

ESTRO 2024

A significant dose reduction (p-value<0.05) with DIBH compared to FB was recorded in all analysed parameters regarding heart (Dmean,Vmax,V5,V10,V20,V30), left lung (Dmean,V5,V10, V20) and LADCA (Dmean,Vmax,V5). In particular, reductions of 42%, 44% and 13% respectively for the mean heart dose (1.6 Gy vs 2.7 Gy, p<0.001), maximum LADAC dose (14.6 Gy vs 26.8 Gy, p<0.001) and mean ipsilateral lung dose (5.5 Gy vs 6.3 Gy, p<0.001) were obtained with DIBH. A greater threshold amplitude of DIBH has not shown to an improvement of dosimetric parameters. The FB-CCDps distance, FB-HCD, and the FB-CCDps/FB-HCD ratio were weakly correlated with the FB mean cardiac dose and the DIBH mean cardiac dose reduction.

Conclusion:

DIBH in postoperative hypofractionated radiotherapy for LSBC leads to significant dose reduction to heart, LADCA and left lung, without compromising target coverage, proving to be an important and effective therapeutic option. Further studies on the effectiveness of the predictive parameters are needed to identify patients who could benefit most from this technique.

Keywords: Breast, DIBH, radiotherapy

2578

Digital Poster

Respiratory gating with CPAP in left breast cancer RT: preliminary results of a prospective study

Bruna Lo Zito 1 , Veronica Richetto 2 , Chiara Cavallin 1 , Elena Gallio 2 , Paola Trevisiol 1 , Cristiano Grossi 1 , Silvia Leardi 1 , Erica Maria Cuffini 1 , Francesca Clot 1 , Paolo Solidoro 3 , Giuseppe Tabbia 3 , Mario Levis 1 , Umberto Ricardi 1 1 University of Turin, Department of Oncology, Turin, Italy. 2 A.O.U. Città della Salute e della Scienza, Medical Physics Unit, Turin, Italy. 3 University of Turin, Department of Medical Sciences, Pneumology, Turin, Italy

Purpose/Objective:

Adjuvant radiotherapy (RT) following breast-conserving surgery (BCS) plays an essential role in reducing local recurrence (LR) rate and increasing overall survival (OS) [1].

In the context of multimodality therapies, especially those involving thoracic RT, there has been a growing interest in sparing organs at risk (OARs) to reduce late toxicity [2]. Among the various solutions for thoracic OARs preservation, several respiratory gating techniques have been used [3].

In left-sided breast cancer, higher cardiac tissue exposure to radiation results in an increased dose to the heart and its substructures, consequently raising the risk of late cardiovascular toxicity [4].

This prospective, observational, monocentric study aims to evaluate dose reduction to the heart and cardiac substructures in patients with early-stage left breast cancer who have undergone BCS or mastectomy and adjuvant