Transbronchial Microwave Ablation of Peripheral Lung Tumors: The NAVABLATE Study

Abstract

Background: Image-guided thermal ablation is a minimally invasive local therapy for lung malignancies. NAVABLATE characterized the safety and performance of transbronchial microwave ablation (MWA) in the lung.

Methods: The prospective, single-arm, 2-center NAVABLATE study (NCT03569111) evaluated transbronchial MWA in patients with histologically confirmed lung malignancies ≤30 mm in maximum diameter who were not candidates for, or who declined, both surgery and stereotactic body radiation therapy. Ablation of 1 nodule was allowed per subject. The nodule was reached with electromagnetic navigation bronchoscopy. Cone-beam computed tomography was used to verify the ablation catheter position and to evaluate the ablation zone postprocedure. The primary end point was composite adverse events related to the transbronchial MWA device through 1-month follow-up. Secondary end points included technical success (nodule reached and ablated according to the study protocol) and technique efficacy (satisfactory ablation based on 1-month follow-up imaging).

Results: Thirty subjects (30 nodules; 66.7% primary lung, 33.3% oligometastatic) were enrolled from February 2019 to September 2020. The pre-procedure median nodule size was 12.5 mm (range 5 to 27 mm). Procedure-day technical success was 100% (30/30), with a mean ablative margin of 9.9±2.7 mm. One-month imaging showed 100% (30/30) technique efficacy. The composite adverse event rate related to the transbronchial MWA device through 1-month follow-up was 3.3% (1 subject, mild hemoptysis). No deaths or pneumothoraces occurred. Four subjects (13.3%) experienced grade 3 complications; none had grade 4 or 5.

Conclusion: Transbronchial microwave ablation is an alternative treatment modality for malignant lung nodules ≤30 mm. There were no deaths or pneumothorax. In all, 13.3% of patients developed grade 3 or above complications.

FIGURE 1

Seventy-five-year-old female, current smoker with emphysema and a 9 mm left upper lobe carcinoid tumor (A). The ablation catheter is placed at the nodule (B), and cone-beam CT shows a ground-glass opacity surrounding the lesion 10 minutes after ablation (C). Follow-up imaging shows consolidation of the ablated nodule (D). CT indicates computed tomography.