2R of Thymidylate Synthase 5'-untranslated Enhanced Region Contributes to Gastric Cancer Risk: a Meta-analysis

BACKGROUND: Studies investigating the association between 2R/3R polymorphisms in the thymidylate synthase 5'-untranslated enhanced region (TYMS 5'-UTR) and gastric cancer risk have generated conflicting results. Thus, a meta-analysis was performed to summarize the data on any association. METHODS: Pubmed, Embase, and CNKI databases were searched for all available studies. The strength of association between TYMS 5'-UTR 2R/3R polymorphism and gastric cancer risk was estimated by odds ratios (ORs) with 95% confidence intervals (CIs). RESULTS: Six individual case-control studies with a total of 1,472 cases and 1,895 controls were included into this meta-analysis. Analyses of total six relevant studies showed that there was no obvious association between the TYMS 5'-UTR 2R/3R polymorphism and gastric cancer risk. Subgroup analyses based on ethnicity showed 2R of TYMS 5'-UTR 2R/3R contributes to gastric cancer risk in the Asian population (ORHomozygote model=1.71, 95%CI 1.19-2.46, P=0.004; ORRecessive genetic model=1.70, 95%CI 1.18-2.43, P=0.004). However, the association in Caucasian populations was uncertain due to the limited studies. CONCLUSIONS: Our meta-analysis suggests that 2R of TYMS 5'-UTR 2R/3R contributes to gastric cancer risk in the Asian population, while this association in Caucasians populations needs further study.