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BARCELONA -- Good outcomes were the rule, not the exception, for select patients undergoing microwave ablation of peripheral lung nodules, results of a single-center study indicated.

Among 52 patients receiving the procedure and followed for up to 4 years -- all considered ineligible for conventional surgery or radiotherapy -- local recurrence occurred for only 18% of nodules ablated and all-cause mortality was 19%, said Kelvin Lau, MBChB, DPhil, of St. Bartholomew's Hospital in London.

Moreover, most of the local recurrences were "part of multisite systemic disease progression," Lau told attendees at the European Respiratory Society's (ERS) annual meeting.

Ablation in these patients is carried out via bronchoscopy, he explained, and is generally safer than trying to excise nodules with percutaneous methods. The latter method, he said, "carries high risk of pneumothorax, pleural effusion, and empyema," whereas the bronchoscopic approach largely avoids these problems.

But he emphasized that bronchoscopic microwave ablation, at least for now, is really appropriate only for those patients who can't undergo conventional surgery or radiotherapy. "Unless they are crawling in [with an] oxygen tank, I will operate on them," joked Lau, a thoracic surgeon. "The primary lung cancer patient [for the bronchoscopic treatment] will be patients with pulmonary fibrosis, who can't have radiotherapy, and very poor lung function. That group is ideal for this."

But, he continued, "at the moment, performance is not as good as either surgery or radiotherapy in terms of the local control rate."

His ERS talk focused on 52 patients he had treated personally at St. Bartholomew's Hospital from February 2018 to February 2022, with a total of 67 nodules targeted for ablation. Of those, 22 were primary lung tumors and the rest were oligometastases. These were ablated in a total of 61 procedures.

Adverse effects included mild hemoptysis in 21% of cases and mild chest pain in 29%; "post-ablation syndrome" occurred in 16%. (The latter constitutes flu-like symptoms, with fever and mild myalgia and fatigue, about a week after the procedure.) Most patients were discharged the next day.

There was one case of pneumothorax, which Lau blamed on himself. He had targeted a nodule on the lung surface adjacent to the spine, he said, and inadvertently penetrated the membrane to cause lung collapse. It resolved without further treatment, he added.

Other complications included one case of pleural effusion to empyema, two infected cavitating lesions, and two cases of bronchial stenosis with segmental collapse.

Median follow-up was 530 days. Three primary tumors and nine metastatic nodules developed local recurrence, with mean time of 326 days. Repeat ablation was performed in two cases -- Lau said one advantage of the microwave procedure is that it can be repeated without limit -- one patient underwent lobectomy for a 4-cm metastasis, five received systemic chemotherapy, and four were "unfit for further treatment," he said.

None of the deaths seen during follow-up were related to the ablation procedure or to the targeted nodules. Median survival was not reached; mean survival time at data cutoff was 880 days for primary lung cancer patients and 1,032 days for those with metastatic lesions. Lau noted that deaths in this patient population generally stem not from their lung tumors, but from the comorbidities that make them ineligible for conventional treatment.

"I think ablation is something we will be doing for the future," Lau replied when an audience member asked whether the bronchoscopic procedure could be first-line therapy for all lung cancer patients. "We need a better technology so that we don't get local recurrence. That might or might not be microwave ablation, it might be another energy source. There will be some way of delivering the energy, we're just not sure which one will have the 100% cure rate."

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