Gated radiation therapy for patients with breast cancer to reduce the dose to the lung and heart: A comparative cross-sectional study

Background: Deep inspiratory breath hold (DIBH) is an established technique to treat left breast cancer with fewer side-effects to the surrounding organs at risk (OARs). However, studies assessing DIBH in resource-poor settings, especially in a government setup, are scarce. Objectives: Our primary objective was to assess and compare the dosimetric changes in the DIBH technique compared to the free breathing technique among patients with left-sided breast cancer undergoing radiation therapy. Materials and Methods: This was a comparative cross-sectional study conducted in the Department of Radiation Oncology, Kidwai Memorial Institute of Oncology (Bengaluru, India), over a period of 24 months. A total of 65 patients were treated with the three-dimensional conformal radiation therapy (3D-CRT) technique either using DIBH or free breathing as per the standard protocol. The dosimetric comparisons for the surrounding OARs, in terms of mean percentage volume receiving 15 Gy (V15Gy) and 20 Gy (V20Gy) in the left lung, V25Gy, V30Gy, V5Gy in the heart the mean dose in Gy received by 25% (V25%) and 40% (V40%) of the heart, V10% and V30% of the left anterior descending artery (LAD) and mean values of Dmean dose (Gy) received by the left lung, heart, and LAD artery were compared between both the techniques. Results: Among 65 patients, 25 (38.4%) were treated by the free breathing technique and 40 (61.6%) by DIBH. Various dosimetric parameters that were significantly lower in the DIBH compared to free breathing techniques included the mean percentage volume of left lung receiving 20 Gy (V20 Gy) (29.5% vs. 23.5%), heart receiving 25 Gy (V25Gy) (6.7% vs. 2.9%) and 30 Gy (12.8% vs. 2.0%), mean values of Dmean received by the heart (7.8 Gy vs. 4.5 Gy) and LAD artery (31.3 Gy vs. 16.9 Gy), mean dose received by 10% volume of LAD (V10%) (36.3 Gy vs. 29.0 Gy) and 30% of LAD artery (V30%) (34.3 Gy vs. 22.2 Gy) (P < 0.001). Conclusion: DIBH significantly decreases the radiation dose delivered to the heart, left lung, and LAD artery. Thus, in patients with left-sided breast cancer, DIBH leads to a lower radiation dose to the OARs, leading to potentially less side-effects.