Efficacy and Safety of Microwave Ablation for Malignant Renal Tumors: An Updated Systematic Review and Meta-Analysis of the Literature Since 2012

OBJECTIVE: To systematically determine the treatment outcomes of percutaneous microwave ablation (MWA) in patients with malignant renal tumor. MATERIALS AND METHODS: Original studies that reported the clinical outcomes of MWA in patients with malignant renal tumors were identified in MEDLINE and EMBASE from 2012 to June 30, 2017. Inverse variance and random-effects models were used to evaluate and acquire meta-analytic summary estimates of various clinical outcomes, including technical outcomes (technical success rate [TSR] and technical efficacy rate [TER]), oncologic outcomes (local tumor recurrence rate [LRR], cancer-specific survival rate [CSSR], and overall survival rate [OSR]), and complications. RESULTS: Among the 145 articles screened, 13 articles including 567 patients carrying 616 malignant renal tumors were included in the meta-analysis. The meta-analytic pooled TSR and TER were 97.3% (95% confidence interval, 94.3–99.4%; I(2) = 0.0%) and 97.6% (95.0–99.4%, I(2) = 48.5%), respectively. The meta-analytic pooled LRR was 2.1% (0.3–4.7%, I(2) = 54.1%). At 1-, 2-, 3-, and 5-year follow-up time points, the meta-analytic pooled CSSRs were 99.1% (97.2–100.0%; I(2) = 0.0%), 98.4% (95.1–100.0%; I(2) = 31.2%), 97.6% (93.4–99.9%; I(2) = 52.3%), and 96.9% (93.3–99.2%; I(2) = 0.0%) respectively, while the OSRs were 98.3% (96.1–99.8%; I(2) = 0.0%), 94.9% (91.7–97.5%; I(2) = 0.0%), 86.8% (81.9–91.1%; I(2) = 22.1%), and 81.9% (75.4–87.6%; I(2) = 0.0%). In terms of major complications, a 1.8% (0.6–3.3%; I(2) = 0.0%) rate of meta-analytic pooled incidence was found. CONCLUSION: Microwave ablation showed favorable technical and oncologic outcomes with a low incidence of major complications. Hence, image-guided percutaneous MWA can be considered as a safe and effective treatment for malignant renal tumors.