Supplementary Material for: Shape-Sensing Robotic-Assisted Bronchoscopic Cryoablation for Primary and Metastatic Pulmonary Nodules: Feasibility, Safety, and Early Outcomes

Background and objective: Minimally invasive bronchoscopic interventions are increasingly explored as alternatives to surgery for pulmonary nodules. Clinical evidence on transbronchial cryoablation guided by robotic-assisted bronchoscopy (RAB) and cone-beam computed tomography (CBCT) remains limited. This study evaluated the feasibility, safety, and long-term effectiveness of shape-sensing RAB-guided transbronchial cryoablation for lung nodules, including metastatic lesions.
Methods: We performed a retrospective review of patients who underwent ssRAB-guided transbronchial cryoablation using ERBECRYO-2 cryotherapy system between July 2023 and May 2025 at the University of California, San Diego. Feasibility was defined as successful probe positioning and completion of cryoablation; safety was assessed by procedure-related adverse events within 14 days, and efficacy was defined as radiographic local control during serial follow-up. Histopathologic findings from nodules subsequently resected were recorded.
Results: Fourteen patients with 15 nodules (mean age, 70.3 ± 8.6 years; mean nodule size, 11.1 ± 4.9 mm) were included. ssRAB-guided cryoablation was successfully performed in all cases (feasibility 100%). No procedure-related serious adverse events occurred; minor adverse events included throat irritation (21.4%), dyspnea (14.3%), and isolated hemoptysis, pleuritic pain, or pulmonary infection (7.1% each). Median follow-up of 110 days (range, 13–487 days). Local control was achieved in 86.7% of nodules. Eight nodules were resected after a median of 79 days, showing fibrosis and inflammation on pathology. Seven nodules were followed radiographically for a median of 358 days, with 85.7% (6/7) remaining stable. Patients receiving immunotherapy demonstrated a trend toward longer local progression-free survival.
Conclusion: ssRAB transbronchial cryoablation using a CO₂-based Erbe system is feasible and demonstrates a favorable safety profile with encouraging early local control across primary and metastatic nodules. The approach enables precise, intraprocedural confirmation of probe placement and may serve as an adjunct to systemic therapies. Prospective multi-center studies are needed to validate these findings, refine cryoablation protocols, establish radiographic and pathologic markers of complete ablation, and clarify the role of transbronchial cryoablation within multidisciplinary lung cancer care.