Continuous positive airway pressure as an alternative to deep-inspiration breath holding for mediastinal lymphoma radiotherapy

PURPOSE: This study explored Continuous Positive Airway Pressure (CPAP) as an alternative to breath-holding (DIBH) techniques by comparing it with free-breathing (FB) in mediastinal lymphoma patients treated with optimized volumetric arc therapy (VMAT). METHODS: Patients underwent computed tomography (CT) simulation in both FB and CPAP (18 cm H2O). The amount of residual respiratory motion with CPAP was assessed using 4D-CT in 27 patients. Lungs, breasts, heart, and cardiac structures were contoured and included in VMAT optimization. Maximum and mean doses were compared for all organs, and CPAP was used if beneficial. Risks of coronary artery disease (CAD) and chronic heart failure (CHF) were estimated via excess relative risk (ERR). RESULTS: The study included 58 patients (22 males, 36 females; mean age 29 years) with Hodgkin (45) or large B-cell lymphoma (13). The median prescribed dose was 30 Gy (range 30-40 Gy). CPAP was well tolerated by all patients. Only nine patients (16%) had no dosimetric benefit from CPAP and were treated in FB. CPAP increased mean lung volume by 1.6 L (4460 vs 2810 cc, p < 0.01) minimized respiratory motion in patients assessed with 4D-CT (mean residual excursion: 388 cc), and significantly reduced lung V20 (10% vs 12.7%, p < 0.01) and V5 (38.2% vs 42.7%, p < 0.01). Moreover, CPAP decreased the intersection of the whole heart with planning target volume (27.9 to 20.9 cc, p < 0.01), which resulted in lower mean doses to the heart (5.3 vs 6.1 Gy, p < 0.01), coronary arteries (7.6 vs 9.5 Gy, p < 0.01), and left ventricle (2.8 vs 3.5 Gy, p < 0.01). CAD and CHF risks significantly reduced with CPAP (p < 0.01). CONCLUSIONS: CPAP significantly reduced radiation doses to lungs and heart, was well tolerated and easy to implement and to use also in department with high patients workload, representing a valid and reproducible alternative to DIBH in mediastinal lymphoma radiotherapy.