Comparative efficacy and safety of microwave ablation versus open surgical resection in colorectal liver metastases: A systematic review and meta-analysis.

144 Background: Colorectal liver metastases (CRLM) represent a major therapeutic challenge in colorectal cancer. While open surgical resection (OSR) remains the preferred treatment method, percutaneous microwave ablation (MWA) has emerged as a minimally invasive alternative. This study aimed to compare the efficacy and safety of MWA versus OSR in patients with CRLM. Methods: This study was conducted in accordance with PRISMA guidelines and registered with PROSPERO. We searched across PubMed, Embase, and Web of Science through May 2025 to identify eligible studies comparing MWA and OSR in patients with CRLM. Primary outcomes included overall survival (OS) at 12, 36, and 60 months, as well as 5-year disease-free survival (DFS). Secondary outcomes included recurrence patterns, complications, operative time, and hospital stay. Pooled estimates were calculated using a random-effects model. The risk of bias was assessed using standard tools, including the GRADE approach. Results: Twenty-one studies comprising 4,014 patients (1,426 MWA; 2,588 OSR) were analyzed. MWA showed a modest survival advantage in 36-month (RR 0.88, 95% CI 0.78–0.98) and 60-month (RR 0.82, 95% CI 0.70–0.96) OS compared to surgery. However, 12-month OS was comparable between both groups (RR 0.98, 95% CI 0.96–1.01). Interestingly, there was no significant difference (RR 0.83, 95% CI 0.62–1.11) in the 5-year DFS between the two groups. We also found that MWA was associated with significantly shorter operative time (MD –101.18 minutes, 95% CI –145.02 to –57.35), reduced hospital stay (SMD –5.78 days, 95% CI –7.12 to –4.45), lower wound infection risk (RR 0.26, 95% CI 0.14–0.45), and fewer overall complications (RR 0.44, 95% CI 0.31–0.61) compared to surgery. OSR, on the other hand, had lower local recurrence (RR 2.74, 95% CI 1.30–5.78) and hepatic recurrence (RR 1.65, 95% CI 1.38–1.98), indicating superior long-term oncologic control. Heterogeneity and risk of bias were substantial, and evidence quality was rated very low across most outcomes. Conclusions: MWA offers meaningful procedural and safety advantages and may be considered for patients who are unfit for major surgery or who prioritize minimally invasive care. Conversely, OSR achieved lower local and hepatic recurrence rates, underscoring its role in durable oncologic control. The apparent survival benefit of MWA despite higher recurrence rates highlights the need for well-designed future studies to mitigate any patient selection bias or unmeasured confounding in existing studies.