title: A population-based case-control study of the Arg399Gln polymorphism in DNA repair gene XRCC1 and risk of breast cancer.
abstract: XRCC1 (X-ray repair cross-complementing group 1) is a base excision repair protein that plays a central role in the repair of DNA base damage and strand breaks. A common polymorphism (Arg-->Gln) at codon 399 of the XRCC1 gene has been previously linked to functional changes of the gene product and risk of cancers. We evaluated the association between XRCC1 Arg399Gln polymorphism and breast cancer risk in the population-based Shanghai Breast Cancer Study involving 1088 cancer patients and 1182 community controls. Genomic DNA from peripheral blood was used in genotyping assays, and exposure information and anthropometrics were collected through in-person interview. Plasma estrogen and sex hormone-binding globulin (SHBG) levels were measured for 190 postmenopausal breast cancer patients who had donated a pretreatment blood sample and 407 postmenopausal controls. Conditional logistic regression model was used to estimate odds ratios (ORs) and 95% confidence intervals (95% CIs) adjusting potential confounders. Approximately 27% of controls carried the variant allele (Gln), and cases and controls had a similar distribution for both allele type and genotype of this polymorphism. We found that 7.8% of cases and 6.3% of controls were homozygous for the variant allele, resulting in an OR of 1.20 (95% CI, 0.85-1.69). The OR was slightly higher among younger women [<45 years of age (OR, 1.39; 95% CI, 0.82-2.36)] than older women [> or = 45 years of age (OR, 1.07; 95% CI, 0.68-1.67)], but neither OR was statistically significant. No modifying effect of major breast cancer risk factors, including years of menstruation, body mass index, waist:hip ratio, and blood estrogen levels, was noted. Homozygosity for the variant Gln allele was associated with an elevated risk of postmenopausal breast cancer among subjects with a higher blood level of SHBG (OR, 3.27; 95% CI, 1.16-9.20) and a reduced risk among those with a lower level of SHBG (OR, 0.60; 95% CI, 0.18-1.97). The overall results of the study suggest that Arg399Gln polymorphism of the XRCC1 gene alone may not play a substantial role in the risk of breast cancer among Chinese women.
authors.affiliation: Department of Medicine and Vanderbilt-Ingram Cancer Center, Vanderbilt University, Nashville, Tennessee 37232-8300, USA. Xaio-Ou.Shu@mail.vanderbilt.edu
authors.forename: Xiao-Ou
authors.initials: XO
authors.lastname: Shu
authors.forename: Qiuyin
authors.initials: Q
authors.lastname: Cai
authors.forename: Yu-Tang
authors.initials: YT
authors.lastname: Gao
authors.forename: Wanqing
authors.initials: W
authors.lastname: Wen
authors.forename: Fan
authors.initials: F
authors.lastname: Jin
authors.forename: Wei
authors.initials: W
authors.lastname: Zheng
mesh_terms: D000328:Adult; D017677:Age Distribution; D000368:Aged; D000483:Alleles; D001943:Breast Neoplasms / Q000453:epidemiology* / Q000235:genetics*; D016022:Case-Control Studies; D002681:China / Q000453:epidemiology; D016001:Confidence Intervals; D004260:DNA Repair; D004268:DNA-Binding Proteins / Q000235:genetics*; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D020022:Genetic Predisposition to Disease; D006801:Humans; D015994:Incidence; D016015:Logistic Models; D008875:Middle Aged; D016017:Odds Ratio; D016133:Polymerase Chain Reaction / Q000379:methods; D011110:Polymorphism, Genetic; D011159:Population Surveillance; D011336:Probability; D011379:Prognosis; D012016:Reference Values; D018570:Risk Assessment; D012680:Sensitivity and Specificity; D016019:Survival Analysis; D000076105:X-ray Repair Cross Complementing Protein 1
chemical_list: D004268:DNA-Binding Proteins; D000076105:X-ray Repair Cross Complementing Protein 1; C000619371:XRCC1 protein, human