To the Editor,

Wu JR et al. [1] conducted a meta-analysis to derive a precise estimation of the prognostic significance of S-1-based therapy over S-1 monotherapy in patients with advanced gastric cancer (AGC) including overall survival (OS) time, progression-free survival (PFS) time, objective response rate (ORR), and adverse events (AEs). Before their results can be accepted, we have several worthwhile queries that we would like to communicate with the investigators.

Firstly, the investigators clarified that “studies stratifying OS, PFS, ORR, and AEs in AGC patients in an S-1-based therapy versus an S-1 monotherapy setting were eligible for analysis by systematic computerized PubMed, Embase, and Cochrane Library searches” in the Abstract section. However, they searched the Cochrane Library, PubMed, Embase, ASCO, and CNKI databases for eligible studies in the Methods section. We would like to know the possible reason for this difference. To make the meta-analysis more credible, the investigators also should give us more search issues such as details for search strategy and manual search protocol. We suggest that the investigators provide us a clear search strategy.

Secondly, the investigators clarified that “studies with less than 30 patients were excluded for the meta-analysis”. We would like to know the possible reason for the exclusion criteria.

Thirdly, the investigators made an AE meta-analysis comparing S-1-based therapy versus S-1 monotherapy as first-line treatment in advanced gastric cancer. However, we could not find the forest plots of the AE meta-analysis in the paper. We suggest that the investigators provide us all the forest plots.

Finally, the investigators clarified that “the presence of publication bias was evaluated using Begg’s test and Egger’s test”. They also described that “no publication bias was detected by either the funnel plot or Egger’s test in OS (P = 0.707 and P = 0.58), PFS (P = 0.452 and P = 1.51), and ORR (P = 0.452 and P = 0.39). However, we cannot find the funnel plots in the paper. We suggest that the investigators provide us all these funnel plots.

Thanks go to the investigators for their contribution in supplying us with an assessment of the prognostic significance of the S-1-based therapy over S-1 monotherapy in patients with AGC. However, larger studies and further clinical trials are still needed to confirm these findings.