title: Polymorphisms of the XRCC1, XRCC3, & XPD genes, and colorectal cancer risk: a case-control study in Taiwan.
abstract: BACKGROUND
  Recent studies relating to the association between DNA repair-gene polymorphisms and colorectal cancer risk would, to the best of our knowledge, appear to be very limited. This study was designed to examine the polymorphisms associated with three DNA repair genes, namely: XRCC1 Arg399Gln, XRCC3 Thr241Met and XPD Lys751Gln, and investigate their role as susceptibility markers for colorectal cancer.
  
  
  METHODS
  We conducted a case-control study including 727 cases of cancer and 736 hospital-based age- and sex-matched healthy controls to examine the role of genetic polymorphisms of three DNA-repair genes (XRCC1, XRCC3 and XPD) in the context of colorectal cancer risk for the Taiwanese population. Genomic DNA isolated from 10 ml whole blood was used to genotype XRCC1 Arg399Gln, XRCC3 Thr241Met and XPD Lys751Gln by means of polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP) analysis.
  
  
  RESULTS
  The risk for colorectal cancer did not appear to differ significantly amongst individuals featuring the XRCC1 399Arg/Arg genotype (OR = 1.18; 95% CI, 0.96-1.45), the XRCC3 241Thr/Thr genotype (OR = 1.25; 95% CI, 0.88-1.79) or the XPD 751Gln allele (OR = 1.20; 95% CI, 0.90-1.61), although individuals featuring a greater number of risk genotypes (genotype with OR greater than 1) did experience a higher risk for colorectal cancer when compared to those who didn't feature any risk genotypes (Trend test P = 0.03). Compared with those individuals who didn't express any putative risk genotypes, individuals featuring all of the putative risk genotypes did experience a significantly greater cancer risk (OR = 2.43, 95% CI = 1.21-4.90), particularly for individuals suffering tumors located in the rectum (OR = 3.18, 95% CI = 1.29-7.82) and diagnosed prior to the age of 60 years (OR = 4.90, 95% CI = 1.72-14.0).
  
  
  CONCLUSIONS
  Our results suggest that DNA-repair pathways may simultaneously modulate the risk of colorectal cancer for the Taiwanese population, and, particularly for rectal cancer and younger patients.
authors.affiliation: Institute of Environmental Health, National Taiwan University College of Public Health, Taipei 100, Taiwan. d88844003@ntu.edu.tw
authors.forename: Chih-Ching
authors.initials: CC
authors.lastname: Yeh
authors.forename: Fung-Chang
authors.initials: FC
authors.lastname: Sung
authors.forename: Reiping
authors.initials: R
authors.lastname: Tang
authors.forename: Chung Rong
authors.initials: CR
authors.lastname: Chang-Chieh
authors.forename: Ling-Ling
authors.initials: LL
authors.lastname: Hsieh
mesh_terms: D016022:Case-Control Studies; D015179:Colorectal Neoplasms / Q000235:genetics*; D004265:DNA Helicases / Q000235:genetics*; D004268:DNA-Binding Proteins / Q000235:genetics*; D005260:Female; D020022:Genetic Predisposition to Disease; D006801:Humans; D008297:Male; D008875:Middle Aged; D011110:Polymorphism, Genetic; D013624:Taiwan; D014157:Transcription Factors / Q000235:genetics*; D000076105:X-ray Repair Cross Complementing Protein 1; D051759:Xeroderma Pigmentosum Group D Protein
chemical_list: D004268:DNA-Binding Proteins; D014157:Transcription Factors; D000076105:X-ray Repair Cross Complementing Protein 1; C110901:X-ray repair cross complementing protein 3; C000619371:XRCC1 protein, human; D004265:DNA Helicases; D051759:Xeroderma Pigmentosum Group D Protein; C497292:ERCC2 protein, human