Microwave Ablation an Alternative Therapy in Lung Malignancy

Liam Davenport

September 09, 2021

Lung cancer patients with relatively small nodules who cannot or will not undergo surgery or radiotherapy can be successfully treated with targeted transbronchial microwave ablation, indicate results from a UK-led preliminary trial.

The NAVABLATE study included 30 patients from the UK and Hong Kong who had malignant lung nodules no more than 30 mm in diameter, who underwent transbronchial microwave ablation and were followed up one month later.

On the day, the technique was performed successfully in all 30 patients, while follow-up imaging at one month suggested that the ablation had been satisfactory in every case, with no repeat procedures necessary.

It was also associated with a "low rate of device-related adverse events and no serious adverse events", said lead author Kelvin Lau, Barts Thorax Centre, St Bartholomew’s Hospital, Barts Health NHS Trust, London.

Consequently, transbronchial microwave ablation can be considered "an alternative treatment modality for patients with primary and metastatic malignant lung nodules…who decline or are ineligible" for surgery and radiotherapy.

The research was presented at the European Respiratory Society International Congress (ERS) 2021 on September 5.

'Encouraging' Results

Professor Stefano Elia, head of the European Respiratory Society’s Assembly on Thoracic Surgery and Transplantation, told Medscape News UK that the results "are encouraging".

However, the patient numbers are "very low, so it is difficult to draw value conclusions", and he would like to have seen more detailed characterisation of the patients’ tumours.

Prof Elia, from the University of Rome Tor Vergata, added that transbronchial microwave ablation should, in line with the study’s inclusion criteria, "probably be reserved" for lung cancer patients "who are unfit for or refuse surgery or alternative treatment strategies".

He added that "prospective, randomised trials are warranted to see if the technique is feasible, safe and indicated" in these patients, and the potential cost of performing it needs to be specified.

Study Details

Presenting the study, Mr Lau explained that NAVABLATE was a prospective, multicentre study that enrolled patients with a confirmed malignant lung nodule ≤30 mm that did not abut the pleura, fissure, or critical structures.

In addition, the patients had declined or were not eligible for both surgery and stereotactic body radiotherapy.

They underwent transbronchial microwave ablation with the Emprint ablation catheter (Medtronic) in a hybrid theatre while undergoing cone-beam computed tomography. Only one nodule was ablated if the patients had more than one.

The team recruited 30 patients at two centres in the UK and Hong Kong, who had a mean age of 68.4 years and of whom 40% were female. The majority (66.7%) were prior or current tobacco users.

Primary lung cancer was the diagnosis in 20 patients, while 10 had oligometastatic disease, and the median nodule size was 12.5 mm. Thirty percent of patients had previously undergone lobectomy, and 16.7% wedge resection.

Thirty-nine ablations were performed in the 30 patients, with 22 having a single ablation. Two ablations were performed in seven patients, while one had three ablations.

The most common ablation times were 10 minutes, in 21 procedures, and 7 minutes, in eight procedures, and the average total bronchoscopy time was 127 minutes.

Technical Success

The procedure was deemed a technical success, defined as the nodule being reached and ablated according to the study protocol, in all patients.

The average ablation margin was 9.9 mm, and one-month follow-up imaging was performed in all patients. This revealed a satisfactory ablation in 100% of cases. No patients required retreatment.

One patient had an adverse event relating to the ablation itself over the one-month follow-up, consisting of grade 1 mild haemoptysis on day 5, which self-resolved.

Adverse events relating to any aspect of the bronchoscopy were seen in 70% of patients, while 13.3% had grade ≥3 events. These included post-procedure pleuritic chest pain in two patients, pleural effusion in two patients, post-ablation syndrome in one patient, and ablation site infection in one patient, all grade 3.

The researchers found that the patients reported only mild pain immediately post-procedure, at an average score of 1.5 on a 10-point scale, falling to 1.4 one week later. At one month, the average pain score was 0.5.

Quality of life as measured on the EQ-5D-3L, was unaffected by the procedure, with scores rising slightly from 74.6 at baseline to 77.4 at the one-month follow-up.

The study was sponsored and funded by Medtronic.

Lau declares relationships with Medtronic, Philips, Johnson & Johnson.

European Respiratory Society International Congress 2021: Abstract 230. Presented 5 September

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