Transbronchial cryoablation in peripheral lung parenchyma with a novel thin cryoprobe and initial clinical testing.

Background: Transbronchial cryoablation shows potential as a local therapy for inoperable peripheral lung cancer. However, its clinical application for peripheral pulmonary lesions has not been reported yet.

Methods: An improved cryoprobe with an 8-mm-long, 1.9-mm-wide cryotip was used. Initially, the safety and effectiveness of this cryoprobe were assessed in an in vivo porcine model. Transbronchial cryoablation with 2 or 3 freeze-thaw cycles (10 min or 15 min in each freezing time) was performed in 18 pigs under CT monitoring. Radiological and pathological examinations were performed to evaluate the extent of cryoablation. Subsequently, nine patients with stage IA peripheral lung cancer or metastases underwent transbronchial cryoablation with this cryoprobe under the guidance of navigation bronchoscopy and cone-beam CT. Technical success, safety and outcomes were assessed.

Results: 36 cryoablation procedures were performed successfully without any major complications in the porcine model. The extent of cryoablation increased with freezing time and the number of freeze-thaw cycles, which peaked at 24 hours and then gradually decreased. Pathological results showed a change from massive haemorrhage at 24 hours to fibrous hyperplasia with chronic inflammation after 4 weeks. In the clinical trial, 10 cryoablations were performed on 9 tumours with a technical success rate of 100%. One mild treatment-related complication occurred. Of the nine tumours, seven achieved complete ablation, while two exhibited incomplete ablation and subsequent local progression at 6 months.

Conclusion: Our initial experience indicated that transbronchial cryoablation was a safe and feasible procedure for non-surgical peripheral stage IA lung cancer or pulmonary metastases.

Trial registration number: ChiCTR2200061544.