Does microwave ablation provide comparable clinical outcomes to surgical resection for colorectal liver metastasis? A systematic review and meta-analysis

Abstract

Presenter: Rebecca Platoff MD | Cooper University Hospital Background: Microwave ablation (MWA) is the preferred ablation tool over radiofrequency ablation (RFA) for resectable liver lesions due to the improved heat sink effect. Previous studies comparing efficacy of ablation compared to surgery have been heterogeneous, including both RFA and MWA when comparing versus surgical resection. However, there is a paucity of data regarding comparison using only MWA versus surgical resection for lesions < 3cm. We aim to compare outcomes after surgical resection versus microwave ablation for colorectal liver metastases by performing a systematic review of the existing literature. Methods: A systematic literature search was performed of PubMed Medline, Embase, and Cochrane Central to report all studies of patients with colorectal liver metastases undergoing microwave ablation or surgical resection. Patients undergoing other therapies, including radiofrequency ablation, were excluded. All study types were included except for case reports and studies in the pediatric population. Results: Of 727 studies reviewed, a full-text review of 60 studies was performed, of which four directly compared microwave ablation and surgical resection for colorectal liver metastases (Table). One study randomly assigned patients to ablative versus surgical treatment, while the other three used retrospective review. Shibata et al, which utilized random assignment, found no statistically significant difference in OS (27 months for MVA vs 25 months for resection, p=0.83). Tinguely et al. originally compared unmatched groups and found improved survival in the group undergoing resection (76% vs 69% at 3 years, p=0.005). After propensity matching, the 3-year OS between the groups disappeared (76% vs 76%, p=0.253). Philips et al. reported increased median survival in the surgery group (43.9 mo vs 37.6 mo, p=0.035) and did not perform matching. Song et al. reported no significant difference in OS or DFS between the groups but did not supply raw data. Complications were generally noted to be higher in the surgical group, with Song et al. reporting a complication rate of 26.5% in the resection group compared with 0% for the MVA group (p=0.003). Tinguely et al. also reported a higher complication rate in the surgery group (16.4% vs 7%, p=0.046). Shibata found a similar complication rate between the two groups (18.8% vs 14.3%, p=0.87), and Philips did not provide this data. Excluded articles did not meet inclusion criteria (25), did not compare the two groups of interest (13), were review articles or guidelines without original data to present (9), or were randomized trials proposed or in the early stages (3). Conclusion: For select patients with colorectal liver metastases, microwave ablation (MVA) offers similar overall survival (OS) and disease-free survival (DFS) when compared to surgical resection alone and appears to provide a lower complication rate. MVA for CLM is currently offered for both resectable lesions that are small (≤3cm) and those potentially resectable or bilateral lesions. MVA is often performed in combination with hepatic resection, with favorable results.