Aims: Thermal ablation is an alternative treatment modality for patients unsuitable for surgical management of colorectal pulmonary metastases. Radiofrequency ablation has been successfully used in the past. Microwave ablation (MWA), offers theoretical advantages over traditional methods of thermal ablation, unstudied in this setting. The aim of this study was to assess the safety and efficacy of MWA in the local control of colorectal pulmonary metastases at 12 month follow-up.
Methods: Retrospective data was collected on all patients undergoing MWA for colorectal pulmonary metastases at a single institution with at least 12 months follow-up. Adverse events within 30 days of MWA were considered procedure-related complications. CT imaging performed immediately prior to MWA was compared with routine progress CTs at 3, 6 and 12 months. Efficacy was measured using modified-RECIST criteria, 12 month progression-free survival and mortality.
Results: Eight patients (n=8) had ten metastases treated with MWA. Median age was 74 (range 56-82) and five were men. Complications included small pneumothoraces requiring no treatment (2/8) and minor haemorrhage requiring no treatment (4/8). One patient required a 14 day admission for management of pulmonary oedema, chest pain and reduced mobility. The other seven patients required 24 hours of routine observation alone. At 12 month patients demonstrated complete response (1/8), partial response (1/8), stable disease (4/8). Two patients demonstrated disease progression at 5 and 10 month post-MWA requiring repeat MWA. Technical difficulty due to lesion location and significant heat sink effect respectively were found to be contributing factors. The 12 month progression-free survival was 75% (6/8) with no deaths (0/8) at 12 month follow-up.
Conclusion: MWA was found to be safe and efficacious in the local control of colorectal pulmonary metastases at 12 month follow-up. MWA may represent an alternative treatment for patients who are unsuitable for surgical management of colorectal pulmonary metastases.