The effectiveness of the DIBH technique in protecting the heart of radiotherapy breast cancer patients treated at the American University of Beirut Medical Center in Lebanon

Introduction While radiation therapy has been shown to increase local control and overall survival for breast cancer, cardiac toxicity remains a concern. Morbidity and mortality have been shown to increase proportionally to the mean heart dose. Deep inspiration breath hold (DIBH) can reduce heart dose compared to free-breathing (FB) delivery by increasing the distance from the heart to the chest wall, especially in left sided breast cancer. DIBH requires monitoring of patients’ respiratory motion. The purpose of this dosimetric study was to verify that DIBH planning technique can serve as an optimized technique concerning PTV coverage and better sparing of concerned OAR's. Retrospective analysis of 103 left-sided breast cancer patients who was treated using FB and DIBH with body surface tracking system. All of them were immobilized in the supine position. Treatment plans were created on FB and DIBH images to compare doses to the heart. Paired T-test was used to compare means and mean differences in heart. A comparison of DIBH and FB plans showed a decrease in mean and heart doses in all patients. Individual patients’ mean heart doses decreased by an average of 0.97 Gy, and the average mean heart dose for DIBH plans was significantly lower than for FB plans (0.74 vs 1.71 Gy; P < 0.001) and decrease of the V4 from 20.79 cc in the plan FB to 3.99 cc in the DIBH plan, it reduced by 16.8 (cc) (i.e. 20.79 (cc) vs 3.99 (cc); p < 0.001) respectively. DIBH with body surface tracking system can significantly benefit patients with left sided breast disease by limiting the V4 heart volume and the mean heart dose. DIBH appears to be a viable option to reduce heart dose for left sided breast cancer patients and thus potentially reduce long-term complications without prolonging treatment delivery.