title: A meta-analysis on XRCC1 and XRCC3 polymorphisms and colorectal cancer risk.
abstract: OBJECTIVE
  Studies on polymorphism of X-ray repair cross-complementing group 1 (XRCC1), group 3 (XRCC3), and colorectal cancer risk are inconclusive. The purpose of this study is to evaluate the role of XRCC1 R399Q, R194W, and XRCC3 T241M genotypes in colorectal cancer susceptibility.
  
  
  METHODS
  We performed a meta-analysis on all available studies that provided 3,514/4,686 cases/controls for R399Q, 2,767/3,907 cases/controls for R194W and 3,183/3,926 cases/controls for T241M.
  
  
  RESULTS
  Overall, no apparent effects of 194 W allele compared to 194R on colorectal cancer risk were found in all subjects and subgroups (Asians and Caucasians). Insignificant effects were also found under other genetic contrasts (homologous contrast, dominant model, and recessive model). The same pattern of results was produced in T241M polymorphism. The 399Q allele compared to 399R showed no significant association with colorectal cancer risk in all subjects and subgroups. However, protective effects of 399QQ genotype were observed under recessive model (QQ/QR + RR) [P = 0.02, OR = 0.84, 95% CI (0.72, 0.97)] and homozygote contrast (QQ/RR) [P = 0.01, OR = 0.81; 95% CI (0.69, 0.95)] in all subjects.
  
  
  CONCLUSIONS
  Results suggested that 399Q allele might act as a recessive allele in its association with colorectal cancer.
authors.affiliation: Department of Colorectal Surgery, Cancer Hospital, Fudan University, 270 Dong An Road, Shanghai 200032, China.
authors.forename: Zheng
authors.initials: Z
authors.lastname: Jiang
authors.forename: Chunxiang
authors.initials: C
authors.lastname: Li
authors.forename: Ye
authors.initials: Y
authors.lastname: Xu
authors.forename: Sanjun
authors.initials: S
authors.lastname: Cai
mesh_terms: D000368:Aged; D016000:Cluster Analysis; D015179:Colorectal Neoplasms / Q000208:ethnology / Q000235:genetics*; D004268:DNA-Binding Proteins / Q000235:genetics*; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D005787:Gene Frequency; D020022:Genetic Predisposition to Disease; D006801:Humans; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D011110:Polymorphism, Genetic; D017594:Publication Bias; D018570:Risk Assessment; D012307:Risk Factors; D000076105:X-ray Repair Cross Complementing Protein 1
chemical_list: D004268:DNA-Binding Proteins; D000076105:X-ray Repair Cross Complementing Protein 1; C110901:X-ray repair cross complementing protein 3; C000619371:XRCC1 protein, human