A clinical trial to compare a 3D‐printed bolus with a conventional bolus with the aim of reducing cardiopulmonary exposure in postmastectomy patients with volumetric modulated arc therapy
Yun Zhang, Yuling Huang, Shenggou Ding, Jinghui Liang, Jie Kuang, Qingfeng Mao, Weiliang Ying, Yuxian Shu, Jingao Li, Chunling Jiang
Abstract
Abstract Background We compared the dosimetry, application, and acute toxicity of a 3D‐printed and a conventional bolus for postmastectomy radiotherapy (PMRT) with volumetric modulated arc therapy (VMAT). Materials and Methods Eligible patients ( n = 75) with PMRT breast cancer were randomly selected to receive VMAT with a conventional bolus or a 3D‐printed bolus. The primary endpoint was a 10% decrease in the mean heart dose to left‐sided breast cancer patients. The secondary endpoint was a 5% decrease in the mean ipsilateral lung dose to all patients. A comparative analysis was carried out of the dosimetry, normal tissue complication probability (NTCP), acute skin toxicity, and radiation pneumonitis. Results Compared to a conventional bolus, the mean heart dose in left‐sided breast cancer was reduced by an average of 0.8 Gy (5.5 ± 1.3 Gy vs. 4.7 ± 0.8 Gy, p = 0.035) and the mean dose to the ipsilateral lung was also reduced by an average of 0.8 Gy (12.4 ± 1.0 Gy vs. 11.6 ± 0.8 Gy, p < 0.001). The values for V 50Gy of the PTV of the chest wall for the 3D‐printed and conventional boluses were 95.4 ± 0.6% and 94.8 ± 0.8% ( p = 0.026) and the values for the CI of the entire PTV were 0.83 ± 0.02 and 0.80 ± 0.03 ( p < 0.001), respectively. The NTCP for the 3D‐printed bolus was also reduced to an average of 0.14% (0.32 ± 0.19% vs. 0.18 ± 0.11%, p = 0.017) for the heart and 0.45% (3.70 ± 0.67% vs. 3.25 ± 0.18%, p < 0.001) for the ipsilateral lung. Grade 2 and Grade 1 radiation pneumonitis were 0.0% versus 7.5% and 14.3% versus 20.0%, respectively ( p = 0.184). Conclusions The 3D‐printed bolus may reduce cardiopulmonary exposure in postmastectomy patients with volumetric modulated arc therapy.