We read with great interest the article by Facciorusso et al. on microwave ablation (MWA) and radiofrequency ablation (RFA) for the treatment of hepatocellular carcinoma [Citation1]. We congratulate them on their interesting and important work in this field, but we feel two issues should be noted.
First, the qualities of randomised controlled trials (RCTs) and case-control studies are different, so we think the results of one RCT and case-control studies on complete response, local recurrence rate and major complications should be interpreted separately. In the ‘Statistical analysis’ section of text, Facciorusso et al. performed sensitivity analysis restricted to high-quality studies, what is the meaning of ‘high-quality studies’? The quality assessment tools of RCTs and case-control studies are different, the authors should provide a definition of the high-quality studies for the Cochrane Collaboration’s tool and the Newcastle–Ottawa scale separately. Compared with case-control studies, RCTs allow better comparability of MWA groups and RFA groups and less confounding bias, information bias and selection bias. In addition, RCTs are prospective studies and case-control studies are retrospective studies, so the quality of ‘moderate-quality’ RCTs is probably higher than ‘high-quality’ case-control studies. In this situation, the moderate-quality RCTs belong to the high-quality studies as the authors have mentioned in the ‘Statistical analysis’ section of the text, but the authors only included high-quality case-control studies when they performed sensitivity analysis restricted to high-quality studies.
Second, RFA is performed by the guidance of ultrasound, computed tomography or magnetic resonance imaging, MWA is performed under computed tomography or ultrasound guidance [Citation2], so the types of devices and the experience of the operators would also affect the results; those factors are probably the sources of heterogeneity and should be treated as limitations when interpreting the results.
Department of Vascular Surgery, First Affiliated Hospital, Guangxi Medical University, Nanning, Guangxi, China
[email protected]
References
- Facciorusso A, Di Maso M, Muscatiello N. Microwave ablation versus radiofrequency ablation for the treatment of hepatocellular carcinoma: a systematic review and meta-analysis. Int J Hyperthermia 2016;1–6
- Ryan MJ, Willatt J, Majdalany BS, Kielar AZ, Chong S, Ruma JA, et al. Ablation techniques for primary and metastatic liver tumors. World J Hepatol 2016;8:191–9.