A Systematic Review of Microwave Ablation for Colorectal Pulmonary Metastases

Abstract

Background/aim: Pulmonary metastases are the second most common site of metastasis in colorectal cancer after the liver, and microwave ablation (MWA) for its treatment has grown in popularity in patients who are not suitable for pulmonary metastatectomy. However, its long-term efficacy remains unknown.

Materials and methods: A systematic review was conducted in July 2022 in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement, using PubMed, EMBASE, Scopus, and Cochrane databases. Studies adopting MWA for colorectal cancer pulmonary metastases were included.

Results: A total of 488 lesions were ablated in 230 patients across eight studies. The median duration of ablation was 10 minutes. The mean length of stay in hospital was 2.3 days. Complications included pneumothorax in 128 (52%) patients; pneumonia, which occurred in 4 (1.7%) patients, and pulmonary haemorrhage in 23 (10.0%) patients. Complete remission was achieved in 85 (37.0%) patients, local control was achieved in 103 (44.8%) patients, and residual or progressive disease remained in 85 (37.0%). Survival post ablation at 1 year was 89.2% and at 3 years was 40.3%. Post-ablation disease-free survival was 43.2% at 3 years.

Conclusion: MWA is an alternative treatment for pulmonary metastases of colorectal cancer. It has competitive theoretical properties and local recurrence rate compared to radiofrequency ablation.

Keywords: Colorectal; cancer; microwave ablation; pulmonary metastasis; review; thermal ablation.