CRD summary This review assessed the effects of postoperative adjuvant chemotherapy on survival rates in gastric cancer and concluded that some slightly significant benefits were observed compared to surgery alone. However, as the authors acknowledged, potential problems with selection bias, poor study quality and small sample sizes may compromise the reliability of their conclusions. Authors' objectives To assess the effects of postoperative adjuvant chemotherapy on survival rates following

more »

... ative resection of gastric cancer in different population groups with different regimens. Results of the review Seventeen RCTs met the inclusion criteria (n=3,529; range 84 to 573). Data were not available for two RCTs, therefore 15 RCTs were included in the analysis (n=3,292; range 84 to 573). All scored two or three on the Jadad scale. Only seven RCTs reported adequate randomisation methods. Adjuvant chemotherapy improved the five-year overall survival rate (RR 0.90, 95% CI: 0.84, 0.96, p=0.001; 15 RCTs) and disease-free survival rate (RR 0.87, 95% CI: 0.78, 0.96, p=0.005; 7 RCTs). No statistically significant heterogeneity between studies was observed for either analysis. Results remained significant when Western and Asian subgroups were analysed separately. When subgrouped by treatment regimen, the meta-analysis suggested slightly better five-year overall survival rates only with mitomycin-Database of Abstracts of Reviews of Effects (DARE) Produced by the Centre for Reviews and Dissemination containing regimens, with or without anthracycline. The numbers of studies within these subgroups were small. The funnel plot showed no evidence of publication bias. Authors' conclusions Postoperative adjuvant chemotherapy for gastric cancer confers slightly significant benefits compared to surgery alone. CRD commentary The review question was clearly defined in terms of participants, intervention and study design. Relevant sources were searched, without language restrictions. There was no specific search for unpublished studies. The authors made some attempts to investigate publication bias. All stages of the review were conducted in duplicate, reducing the potential for error and bias. Validity was assessed using established criteria, and the results for some of the Jadad criteria were reported for each study. Risk ratios were used to assess survival rather than hazard ratios. Investigations into the impact of clinical heterogeneity made despite the lack of statistical heterogeneity in the main analyses, however, many of the subgroup analyses consisted of only two studies, limiting the reliability of the pooled results. Ten authors acknowledge a number of limitations, including the possibility of selection bias, the lack of data on Asian populations and small sample sizes. These factors might impact the reliability of the authors' conclusions. Practice: The authors stated that with the currently available evidence, they cannot conclude adjuvant chemotherapy for localised resected gastric cancer as a standard option. Research: The authors recommended a meta-analysis of individual patient data before conducting further RCTs. They also stated that a large, well conducted RCT is needed to define the most effective strategies for gastric cancer. Funding Not stated Bibliographic details Zhao S L, Fang J Y . The role of postoperative adjuvant chemotherapy following curative resection for gastric cancer: a meta-analysis. This is a critical abstract of a systematic review that meets the criteria for inclusion on DARE. Each critical abstract contains a brief summary of the review methods, results and conclusions followed by a detailed critical assessment on the reliability of the review and the conclusions drawn.