Comment on: "Stereotactic body radiation therapy versus radiofrequency ablation in patients with small hepatocellular carcinoma: a systematic review and meta-analysis".

We are grateful to Hepatobiliary Surg Nutr for publishing the study entitled “Stereotactic body radiation therapy versus radiofrequency ablation in patients with small hepatocellular carcinoma: a systematic review and meta-analysis”. In this well-designed study, the authors concluded that in patients with small hepatocellular carcinoma, stereotactic body radiation therapy has a higher local control rate but poorer prognosis than radiofrequency ablation; in addition, the local toxicity of the two treatments was comparable (1). While we read the article with pleasure, it must be noted that this study raises some thought-provoking issues.

There is common agreement that systematic reviews must be conducted and reported according to the highest methodological standards. For example, review registration is mandatory, and detailed study registration information should be highlighted and explained in the article. Registering a systematic review protocol is important as it enables the promotion of transparency and avoidance of potential biases including both selection and selective outcome reporting biases.

Second, the authors should further optimize the search strategy and expand the scope of the databases to avoid the omission of qualified literature. In this meta-analysis, the databases mentioned in the authors’ article are still inadequate in our view. If some other English databases including Google Scholar, Scopus, NLM Gateway and PsycINFO can also be searched, then it may increase the target articles and thus improve the persuasiveness of the outcomes. In addition, the authors stated in the text that there were no language restrictions, thus many Chinese databases such as Wanfang, CNKI, Taiwan Electronic Periodical Services, and China National Knowledge Infrastructure should also be searched.

We also recommend that authors should detail the quality assessment protocol for the included literature in the methods section of the article. The authors stated that five retrospective studies were included, but the evaluation method used was only applicable to randomized controlled trials. We recommend using a Newcastle-Ottawa scale (2) or a modified version of the Downs and Black tool (3) to assess the quality of the studies. In addition, the authors considered the three included studies were randomized; however, we suggest that the authors should carefully evaluate the quality of each article, since randomization is not possible in retrospective studies.

We are grateful to Hong et al. for contributing to this important meta-analysis that can guide clinical decision-making. However, high-quality studies with large sample sizes are still needed to continue to clarify this issue.

The article’s supplementary files as