Efficacy and safety of novel airway balloon cryoablation system for malignant central airway obstruction: a prospective, multicentre, randomised, non-inferiority study

Background A novel airway balloon cryoablation (ABC) system using liquid nitrogen as cryogen was developed for bronchoscopic intervention in malignant central airway obstruction (MCAO). This study aimed to evaluate the efficacy and safety of this system. Methods This was a prospective, randomised, controlled, non-inferiority study that enrolled MCAO patients at 15 sites in China. Patients were assigned to the ABC group and the ERBOKRYOCA Cryosurgical (EC) system group in a 1:1 ratio. Airway tumour debulking with multimodality was permitted before cryoablation. The primary outcome was the airway patency rate after 6 weeks of intervention with a non-inferiority margin of −10%. Secondary outcomes included modified Medical Research Council (mMRC) Dyspnoea Scale and Karnofsky Performance Scale (KPS) assessment, and the duration of cryoablation. Results 198 patients were randomised. After 6 weeks of intervention, the airway patency rate was 78.49% in the ABC group and 60.92% in the EC group, showing that the difference was over the non-inferiority margin of −10% at 17.58% (95% CI 4.35% to 30.80%), p<0.001. The mMRC and KPS scores were significantly improved after 3 and 6 weeks in both groups, with no difference. The duration of cryoablation was shortened remarkably in the ABC group (378.29±399.54 s vs 624.93±443.72 s, p<0.001). The prevalence of bleeding was similar in the two groups, without life-threatening events. Conclusions The ABC system provided non-inferior and subsequent superior effect in airway patency rate compared with traditional carbon dioxide-driven cryoprobe in MCAO. This study supports this novel system as an alternative to cryoablation via bronchoscope for MCAO patients. Trial registration number ChiCTR2100042051. Data are available on reasonable request.