Technical and safety performance of CT-guided percutaneous microwave ablation for lung tumors: an ablate and resect study.

Background: Percutaneous image-guided thermal ablation has an increasing role in the treatment of primary and metastatic lung tumors. Achieving acceptable clinical outcomes requires better tools for pre-procedure prediction of ablation zone size and shape.
Methods: This was a prospective, non-randomized, single-arm, multicenter study conducted by Medtronic (ClinicalTrials.gov ID: NCT02323854). Subjects scheduled for resection of metastatic or primary lung nodules underwent preoperative percutaneous microwave ablation. Ablation zones as measured via CT imaging following ablation immediately and before resection surgically versus predicted ablation zones as prescribed by the investigational system software were compared. This CT scan occurred after the ablation was finished but the antenna still in position. Time (minutes) from antenna placement to removal was 23.7±13.1 (n=14); median: 21.0 (range, 6.0 to 48.0). The definition of the secondary endpoint of complete ablation was 100% non-viable tumor cells based on nicotinamide adenine dinucleotide hydrogen (NADH) staining. Safety endpoints were type, incidence, and severity of adverse events.
Results: Fifteen patients (mean age 58.9 years; 67% male; 33% female) were enrolled in the study, 33.3% (5/15) with previous thoracic surgery, 73% (11/15) with metastasis, and 27% (4/15) with primary lung tumors. All underwent percutaneous microwave ablation followed by surgical resection the same day. Complete ablation was detected in 54.4% (6/11), incomplete ablation in 36.4% (4/11), and delayed necrosis in 9.1% (1/11). There were no device-related adverse events. Ablation zone volume was overestimated in all patients.
Conclusions: Histological complete ablation was observed in 55% of subjects. CT scanning less than an hour after ablation and tissue shrinkage may account for the smaller zone of ablation observed compared to predicted by the investigational system software.
Competing Interests: Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://dx.doi.org/10.21037/jtd-21-594). RMS is an inventor on patents and royalties in the field of CAR-T cell therapy licensed to Humanigen through Mayo Clinic. JLP has leadership/fiduciary roles and Stock/stock options in TMRW, Angiocrine Bioscience, and View Point Medical. DED has grants/contracts with Varian Inc.; royalties/licenses with Springer Verlag and Uptodate; consulting fees from Varian Inc; payment/honoraria from Moffitt Cancer Center; holds multiple patents (patent number 11076916 publication number 20190216537, patent number 10722289 publication number 20180153617, publication number 20200179049, publication number 20170182165); is the president and board member of Theromics Inc and the SIO program committee; and has stock/stock options with Theromics Inc. MRC has grants/contracts with Galil Medical, EDDA; royalties/licenses with Uptodate; consulting fees from Boston Scientific, Medtronic, Varian, and Pulse Biosciences; and a leadership/fiduciary role in the Society of Interventional Oncology. The other authors have no conflicts of interest to declare.
(2021 Journal of Thoracic Disease. All rights reserved.)