Association Between Cytotoxic T Lymphocyte Antigen-4 Gene Polymorphisms And Gastric Cancer Risk: A Meta-Analysis Of Case-Control Studies

Many previous studies have reported the existence of CTLA-4 polymorphisms in various cancers. However, the effects of CTLA-4 polymorphisms on the risk of gastric cancer (GC) remain conflicting and have not been studied in detail. This meta-analysis was performed to clarify the association between CTLA-4+ 49A/G, - 1661A/G and -1722T/C polymorphisms and GC risk. A systematic literature search for eligible studies published before October 10, 2015. We assessed the possible association by pooled odds ratio (OR) and its 95% confidence interval (95% CI) using the fixed or random effect model. A total of 9 independent case-control studies were enrolled in the final meta-analysis. Overall, no significant association between +49A/G polymorphism and GC risk was identified in all genetic models. However, increased GC risk was found in the subgroups of Caucasian populations and Hospital-Based (HB). For the -1661A/G polymorphism, pooled estimates showed that the -1661A/G polymorphism was significantly associated with an increased GC risk under allele comparison, heterozygote comparison and dominant models. Similar results were also found in subgroup analyses according to ethnicity, source of control and genotyping method. For the -1772T/C polymorphism, a significantly decreased risk of GC was observed under homozygote comparison and recessive model, especially in Asian populations and HB subgroups. The results suggest that both -1661A/G and -1722T/C polymorphisms in CTLA-4 are risk factors for GC. While no significant association was detected in the overall results of +49A/G polymorphism, an increased GC risk was found in Caucasian populations and HB subgroups.