Investigation of cardiac and pulmonar doses in patients with left sided breast cancer treated by radiotherapy with deep inspiration breath hold technique

Background: Cardiac disease is a documented risk factor in left breast irradiation. In an attempt to reduce cardiac toxicity, different treatment techniques adapted to respiratory cycle phases have been developed. The aim of this study is to investigate the feasibility of the voluntary breath hold technique when irradiating the left breast in selected patients. Material and Methods: The study included 20 patients with left sided breast cancer. For each patient, two computed tomography (CT) scans were acquired, one with the free breathing (FB) technique and one with the voluntary deep inspiration breath hold (DIBH) technique. Treatment plans were created using a field-in-field intensity-modulated radiation therapy technique. A dosimetric comparison was made between the two techniques for the heart, left anterior descending (LAD) coronary artery, ipsilateral lung and contralateral breast. Results: The average of the mean dose of the heart decreased from 7.7 Gy to 5.8 Gy and V-20(Gy) (%) from 12.8% to 8.3% using the DIBH technique (p=0.009, p<0.001). The DIBH technique demonstrated significantly smaller maximum heart distance (2.0 cm vs. 0.9 cm, p < 0.001) and 8.0% reduction in LAD mean dose. Furthermore, D-mean for the ipsilateral lung was reduced from 12.8 Gy to 12.2 Gy and V-20(Gy) (%) from 25.6% to 22.8%. Conclusion: In the treatment plans made using the DIBH technique, a significant reduction in the radiation dose delivered to the heart has been observed. In order to reduce long-term morbidity and mortality risks from cardiovascular disease affecting the survival of patients with left sided breast cancer, irradiation techniques such as the DIBH should be considered, especially for premenopausal patients.