Is microwave ablation more effective than radiofrequency ablation in achieving local control for primary pulmonary malignancy?

A best evidence topic in thoracic surgery was written according to a structured protocol. The question addressed was 'Is microwave ablation (MWA) more effective than radiofrequency ablation (RFA) in achieving local control for primary lung cancer?'. Altogether, 439 papers were found, of which 7 represented the best evidence to answer the clinical question. The authors, journal, date and country of publication, patient group studied, study type, relevant outcomes and results of these papers are tabulated. Both are thermal ablative techniques, with microwave ablation (MWA) the newer technique and radiofrequency ablation (RFA) with a longer track record. Lack of consensus with regard to definitions of technical success and efficacy and heterogeneity of study inclusions limits studies for both. The only direct comparison study does not demonstrate a difference with either technique in achieving local control. The quality of evidence for MWA is very limited by retrospective nature and heterogeneity in technique, power settings and tumour type. Tumour size and late-stage cancer were shown to be associated with higher rates of local recurrence in 1 MWA study. RFA studies were generally of a higher level of evidence comprising prospective trials, systematic review and meta-analysis. The recurrence rates for MWA and RFA overlapped, and for the included studies ranged between 16% and 44% for MWA and 9% and 58% for RFA. The current evidence, therefore, does not clearly demonstrate a benefit of MWA over RFA in achieving local control in primary lung cancer.