A Phase I/II Trial to Evaluate the Safety and Efficacy of Continuous Positive Airway Pressure in Volumetric Modulated Arc Therapy for Breast Cancer.

[PURPOSE] This phase I/II study aimed to evaluate the tolerability and the organ-sparing effects of continuous positive airway pressure (CPAP) in breast cancer radiotherapy (RT).

[MATERIALS AND METHODS] We conducted a prospective, single-institutional trial approved by the Ministry of Food and Drug Safety of South Korea. Patients with breast cancer who received postoperative RT underwent 4D-CT simulation and treatment planning under both free breathing (FB) and CPAP-assisted breathing (WC), with a target pressure of 20 cm H2O. Adverse events (AEs) were evaluated, and dosimetric parameters of organs at risk and heart position change were compared between the FB and WC arms.

[RESULTS] Among 20 enrolled patients, four withdrew due to discomfort during simulation. During the trial, no CPAP-related AEs greater than grade 2 were observed. Compared to FB, CPAP reduced the mean heart dose by 33.8% (p < 0.001), as well as V5-V30 for both the left ventricle and left anterior descending artery (all p < 0.05). It also led to significant reductions in V5-V40 and the mean ipsilateral lung dose, including a 4.4% reduction in V20 (all p < 0.001). The heart centroid shifted rightward (4.8 mm), ventrally (8.1 mm), and caudally (16.3 mm) with CPAP, displacing the heart away from the RT field.

[CONCLUSION] CPAP demonstrated both safety and efficacy for breast cancer RT, achieving significant reductions in cardiac and pulmonary radiation exposure. These findings support further investigation of CPAP as a novel respiratory motion management strategy. Future studies are warranted to identify optimal CPAP pressure levels to facilitate broader clinical implementation.