Review for 10.1186/s12876-024-03250-7 (2024)

Title: Title: Systematic Review and Meta-analysis: The Efficacy and Safety of Radiofrequency
Ablation for Early Superficial Esophageal Squamous Cell Neoplasia
Version: 1 Date: 18 Feb 2024
Reviewer's report:
In this article, the authors conducted a systematic review and meta-analysis for radiofrequency
ablation (RFA) for esophageal squamous cell neoplasm (ESCN).  I have several concerns below:
1. In the abstract, I assume the outcome parameter should be "rate". This should have been
noted following the outcome, or the results should be expressed with percent. Namely, "The
pooled histological CR were 0.83..." should  either be "The pooled histological CR rate were
0.83", or "The pooled histological CR rate were 83%". The format of outcome expression should
therefore be revised.
2. In the conclusion,  "endoscopic RFA achieved both higher 12-month complete remission and
late complication postoperatively...". What is the object to be compared with RFA here? If there
was no comparison, it should be expressed as "high" instead of higher. If the authors means the
comparison between RFA and ESD, the sentence may be revised to be clearer.
3. The p value cut-off for statistical heterogeneity is typically
set at 0.1 by Cochrane handbook (https://handbook-5-1.cochrane.org/
chapter_9/9_5_2_identifying_and_measuring_heterogeneity.htm) Please state your argument
and reference to set the cutoff at 0.05 here.
4. The rationale of the variable selection (ER and male gender) is subgroup analysis is unclear.
Besides, the meaning of ER < 25% or >= 25% is confusing. Does it mean 25% circumference
or 25% patients experienced ER? Please explain.
5. In The Figure 1. and Results, I could not tell whether there were 17 ( 9+8) or only 9 studies
were eligible for final analysis. The statement was really confusing. It is common that not
all eligible studies are suitable for meta-analysis. However, it is not necessary to express two
numbers for eligible studies for systematic review and meta-analysis. I strongly recommend
correcting it.
6.In terms of the sensitivity analysis, the authors perform a common approach that excluding
one study at each time to identify which study is responsible for heterogeneity. However, once
the study is identified, it should be explained in discussion why this study becomes the outlier,
rather than just performing staticstical evaluation.
7. Furthermore, the sentence: "The results showed there was an improvement in both the
heterogeneity of the 12-month histological CR (RR 0.98, 95% CI: 0.92-1.05, I2=0%, p=0.57)
and late postoperative AEs (RR 0.57, 95% CI: 0.38-0.87, I2=0%, p<0.01), with statistical
significance." was confusing. The 12-month histological CR did not have statistical sigficance.
Please revise it.
8. The comparison of ESD and RFA is only clinical meaningful if clear and accurate preoperative
diagnosis is fully disclosed, since RFA is considered inadequate for lesions invade more than
mucosal layer. Moreover, the weakness of RFA is inability to obtain histologic specimen. Hence,
it is important to have comprehensive comparison of included patients in trials comparing ESD
and RFA. Unfortunately, I could not find it in the tables.
9. In conclusion, I think the authors attempted to make a meticulous analysis for this topic, as
shown by lots of supplementary tables. Unfortunately, there were several foundamental flaws
were noted in the previous comments. It may be highly helpful if the authors invite clinical expert
in endoscopic treatment for early ESCN and experience scholar for meta-analysis to improve
the article more.