Long-term Survival Results following Endobronchial RF Ablation in a Healthy-Porcine Model

Abstract

This paper presents results from long-term survival study where healthy swine were ablated with a novel technology designed for treating early-stage non-small cell lung cancer using an endobronchial flexible catheter. Methods-The radiofrequency ablation (RFA) system has been presented previously and consisted of an ablation catheter, radiofrequency generator, irrigation pump for infusion of hypertonic saline (HS) and a laptop. The catheter carried an occlusion balloon, a 5 mm long RF electrode, with irrigation holes, and a 1 mm long electrode for bipolar impedance measurements. The outer diameter (OD) was 1.4 mm for compatibility with current bronchoscopes, navigation systems and radial EBUS. Nine swine were treated in this study with survival times of 1, 4 and 12 weeks (N=3 at each time point). In all animals, the treatment sites consisted of one location in the upper right lung (RUL) and another one in the lower right lung (RLL). CTs were taken pre-op, immediately post-op and at every 2 weeks post treatment. Ablation times ranged from 6 to 8 min and average applied power was 68 W (range 63-72 W). Results-At 1-week survival, large zones of necrotic tissue were observed in all respective 6 ablations. Ablation volumes had an average diameter of 3.2 cm at RUL locations and 3.8 cm in RLLs (likely due to longer RLL ablation durations). As time progressed, the necrotic tissue was gradually replaced with fibrotic tissue. At 4-week survival, the replacement was almost complete in all respective 3 animals. As a result, ablation volumes decreased to an average diameter of 1.3 cm at RUL locations and 2.3 cm in RLLs (likely due to longer RLL ablation durations). At 12-week survival, as the replacement process continued, histopathology revealed zones of residual necrotic tissue that were further reduced in size. Ablation zones had been resorbed and contracted by fibrous scar tissue. The average volume of the treatment effect decreased to 1.1 cm (RUL) and to 1.6 cm (RLL) in equivalent diameter. There were no complications in any of the nine animals. Conclusion-In healthy swine lungs, RFA with a 1.4-mm OD, radial-EBUS-sheath-compatible, endobronchial catheter was effective and safe. This system and therapeutic approach may be considered for further evaluation in minimally invasive treatment of tumorous lung nodules.

Transbronchial microwave ablation of lung nodules with electromagnetic navigation bronchoscopy guidance—a novel technique and initial experience with 30 cases

“…Most of the thermal ablative techniques in literature applied the electrode in a percutaneous manner. Lately, transbronchial ablation techniques using different energy source have been researched in animal lung models (24)(25)(26). In humans, bronchoscopy-guided transbronchial ablation have been attempted by a Japanese and a Chinese group, utilizing RFA energy with reported safety (27)(28)(29).…”

Novel Image-Guided Flexible-Probe Transbronchial Microwave Ablation for Stage 1 Lung Cancer

“…Preliminary studies with transbronchial-delivered RFA of early-stage NSCLC have provided promising short-term results [19,20], but clinical experience with transbronchial MWA (tMWA) remains limited to retrospective single-center observations and conference proceedings [21][22][23]. Preclinical studies have assessed the radiological and histological aspects of tMWA-induced lung tissue damage and recovery [24][25][26][27]. Here, we present a prospective feasibility study on the safety and shortterm efficacy of tMWA guided by cone-beam CT (CBCT) with augmented fluoroscopy (AF) for the ablation of peripheral stage 1 lung cancer [28].…”

Safety and Feasibility of a Novel Externally Cooled Bronchoscopic Radiofrequency Ablation Catheter for Ablation of Peripheral Lung Tumours: A First-In-Human Dose Escalation Study

“…There is a clear need to improve upon percutaneous approaches by creating a new RFA paradigm specifically for the lungs. We have previously reported on a novel RFA catheter with a saline-cooled electrode that was able to achieve relatively large, uniform ablation zones in an in vivo porcine model, confirming feasibility and long-term safety of this approach [ 8 , 9 ], and permitted extensive dose mapping studies to be completed. Herein, we report outcomes of bronchoscopic RFA ablation of peripheral tumours following a first-in-human dose escalation study.…”