title: 3R variant of thymidylate synthase 5'-untranslated enhanced region contributes to colorectal cancer risk: a meta-analysis.
abstract: BACKGROUND
  Studies investigating the association of 2R/3R polymorphism in the thymidylate synthase 5'-untranslated enhanced region (TSER) and colorectal cancer (CRC) risk have reported conflicting results. Thus, a meta-analysis was performed to summarize the data on the potential association.
  
  
  METHODS
  Pubmed, Embase and CBM databases were searched for all available studies. Links between the TSER 2R/3R polymorphism and CRC risk were estimated by odds ratios (ORs) with 95% confidence intervals (CIs).
  
  
  RESULTS
  Seven case-control studies with a total of 2723 cases and 4030 controls were included in this meta-analysis. The results showed that the 3R variant of TSER 2R/3R polymorphism contributes to CRC risk in two comparison models (OR 3R vs. 2R =1.10, 95%CI 1.02-1.18, P = 0.015; OR Homozygote comparison model = 1.22 1.04-1.43, 95%CI 1.04- 1.43, P = 0.012). Subgroup analyses by ethnicity further demonstrated a contribution in Caucasians with three comparison models (OR 3R vs. 2R = 1.10, 95%CI 1.02-1.19, P = 0.015; OR Homozygote comparison model = 1.21, 95%CI 1.03-1.41, P = 0.019; OR Recessive comparison model = 1.18, 95%CI 1.05-1.33, P = 0.008). However, the association in the Asian population was still uncertain due to the limited data (all P values were more than 0.05).
  
  
  CONCLUSIONS
  Our meta-analysis suggests that the 3R variant of Thymidylate synthase 5'-untranslated enhanced region 2R/3R polymorphism contributes to gastric cancer risk in the Caucasian population, while any association in Asian populations needs further study.
authors.affiliation: Department of Colorectal Surgery, the First Affiliated Hospital of China Medical University, Shenyang, China.
authors.forename: Min
authors.initials: M
authors.lastname: Lu
authors.forename: Luhaoran
authors.initials: L
authors.lastname: Sun
authors.forename: Jing
authors.initials: J
authors.lastname: Yang
authors.forename: Yue-Yao
authors.initials: YY
authors.lastname: Li
mesh_terms: D020121:5' Untranslated Regions; D016022:Case-Control Studies; D015179:Colorectal Neoplasms / Q000235:genetics*; D020022:Genetic Predisposition to Disease; D005838:Genotype; D006801:Humans; D020641:Polymorphism, Single Nucleotide; D012306:Risk; D013940:Thymidylate Synthase / Q000235:genetics*
chemical_list: D020121:5' Untranslated Regions; D013940:Thymidylate Synthase