No association between XRCC1 and XRCC3 gene polymorphisms and breast cancer risk: Iowa Womenʹs Health Study

Background: Genetic variation in DNA repair may contribute to differences in the susceptibility of several cancers. We evaluated two polymorphisms in the base excision repair pathway (BER) (XRCC1; Arg194Trp and Arg399Gln) and one polymorphism in the double strand DNA repair pathway (XRCC3; Thr241Met) for their association with breast cancer risk. Methods: The association was analyzed in a nested case control study of 460 breast cancer cases and 324 cancer-free controls within the Iowa Womenʹs Health Cohort. DNA was obtained from blood samples or paraffin embedded tissues (PET) and all samples were genotyped by one of three genotyping platforms—PCR-RFLP, PCR-INVADER, or Sequenom. Results: None of the three polymorphisms studied were significantly associated with breast cancer risk (XRCC1: Arg194Trp (OR = 1.21, 95% CI: 0.78–1.88); Arg399Gln (OR = 1.20, 95% CI: 0.80–1.79); XRCC3: Thr241Met (OR = 1.04, 95% CI: 0.76–1.41). Conclusions: These results suggest that independently these polymorphisms of XRCC1 and XRCC3 genes do not contribute significantly to the genetic susceptibility of breast cancer.