Abstract

ghada abdessatar¹, Rim Moujahed¹, Mouna Ben Rejeb¹, Awatef Hamdoun¹, Jamel Yahyaoui¹, Zeineb Naimi¹, Lotfi Kochbati¹

¹Abderrahmane Mami Hospital, radiation-oncology department, Ariana, Tunisia

Radiotherapy (RT) for breast cancer reduces the risk of local recurrence and the risk of breast cancer mortality. However, it could induce excess cardiovascular mortality and morbidity. The purpose of this study was to evaluate the benefit of voluntary deep inspiration breath-hold (DIBH) over a free-breathing (FB) technique to minimize cardiac substructures exposure in radiation therapy of left-sided breast cancer.

Thirty-three patients with left-sided breast cancer underwent DIBH and FB planning computed tomography scans. Cardiac substructures were contoured using the F. Duane's cardiac atlas. Treatment planning was generated for both CT scanners using 3D-conformal radiotherapy (50 Gy delivered in 25 fractions ± boost of 16 Gy). Dose-volume histograms were analysed for heart, left anterior descending coronary artery (LAD), left circumflex (LCx), left main coronary artery (LMCA), right coronary artery (RCA), left ventricule (LV) and left lung.

Dose to heart, LAD, LCx, LMCA, RCA, LV, and left lung was significantly lower in DIBH plans than in FB. When DIBH was compared with FB, mean dose (Dmean) for heart was 3.08Gy [1.1-  4.2] versus 4.1Gy [ 1.2-5.9 ]; for LAD (Dmean/Dmax) 9.9Gy /21.5Gy versus 14.7Gy/ 33.6Gy (p<0.01); for LCx 1.1Gy/ 1.94Gy versus 1.25Gy/ 2.04 Gy (p=0.1); for LMCA 1.5Gy/ 1.88 Gy versus 1.78Gy/ 2.15 Gy (p<0.01); for RCA  1.2Gy /2.03Gy versus 1.33Gy /2.2 Gy (p<0.01) and for LV,  2.2Gy/ 23.6Gy versus  4.8Gy/ 35.2Gy ( p< 0.01), respectively. DIBH decreased Dmean for lung by 3.1Gy (8.9 Gy versus 12Gy). The V20Gy was 16.87% versus 18.38%. The V30Gy was 11.9 % versus 13.47%.

Deep-inspiration breath hold technique improves cardiac substructures dosimetry compared to FB. We support the preferential use of DIBH, especially, in patients with cardiovascular comorbidities. The mean cardiac dose is probably insufficient to assess the exposure of cardiac substructures. Therefore, we recommend to consider doses to LAD and LV in the planning optimization for left-sided breast radiotherapy