Population differences concerning TNF-α gene polymorphisms in gastric carcinogenesis based on meta-analysis

Background Recent meta-analyses have studied population differences concerning interleukin (IL)-1 gene polymorphisms in gastric carcinogenesis. In addition to the IL-1 gene cluster, candidate genes include those encoding the pro-inflammatory cytokine tumor necrosis factor (TNF)-α. The aim of the study was to systematically review the role of TNF-α-238 and TNF-α-308 gene polymorphisms (genotypes G/G, G/A, A/A) in gastric carcinogenesis by meta-analyzing all relevant studies to look for any differences concerning TNF-α gene polymorphisms in gastric carcinogenesis. Methods Extensive English language medical literature searches for human studies were performed up to the end of May 2013, using suitable keywords. Pooled estimates [odds ratio (OR) with 95% confidence intervals (CI)] were obtained using the random-effects model. Heterogeneity between studies was evaluated with the Cochran Q test whereas the likelihood of publication bias was assessed by constructing funnel plots. Their symmetry was estimated by the adjusted rank correlation test.