Comment on Regarding Manuscript “Liver Resection Versus Local Ablation Therapies for Hepatocellular Carcinoma Within the Milan Criteria: A Systemic Review and Meta-analysis”

To the Editor: Shin et al1 reported a total of 7 randomized controlled trials (RCTs) and 18 matched NRTs, involving 2865 patients with HCC in the liver resection group and 2764 patients in the local ablation therapy group to compare the oncologic outcomes. We appreciate the writing intention of this meta-analysis. However, several methodological issues in the article are worthy of comment. The original documents selected by the meta-analysis have a large extent of publication bias, but the author has no relevant explanation for the publication bias that may occur in the article. In fact, the risk of bias should be part of the conduct and reporting of any systematic review,2 as the PRISMA statement recommended and required. The literature included in this paper includes RCT and cohort studies. Therefore, this study would be more convincing if the results of the new Cochrane risk of bias tool to review the risk of RCT bias and the results of the Newcastle-Ottawa Scale review of the cohort study are added to the content of this article.3–5 In addition, there are no funnel plots or other methods to detect publication bias, which also should be reflected in the meta-analysis. If the author fails to evaluate the publication bias due to other objective reasons (such as too little research content included), an appropriate explanation should be made in the corresponding part of the article.