Polymorphisms of XRCC2 gene and breast cancer risk : a case-control study in Han women of northwest China

Background: The XRCC2 gene plays an important role in the homologous recombination repair of DNA double strand breaks. Functional single nucleotide polymorphisms (SNPs) of XRCC2 may alter DNA repair capacity and affect cancer susceptibility. This study aims to evaluate the association between five tagSNPs in XRCC2 and breast cancer susceptibility in Han women of northwest China. Methods: A total of 514 histopathologically confirmed breast cancer patients and 1028 region- and age-matched cancer-free controls provided blood samples for analysis of SNP genotypes in this case-control study using a QuantStudio™ 12K Flex Real-Time PCR System. Results: After adjusting covariates, 2 SNPs in XRCC2 (rs3218536 and rs6964582) showed significant associations with the risk of breast cancer. In haplotype analysis, CGTTC haplotype conferred an increased risk of breast cancer(P=5.83×10 -3 ), whereas TGTTA haplotype was associated with a decreased risk of breast cancer(P=1.17×10 -3 ). Significant associations were shown between CGTTA, CCTTA haplotypes of XRCC2 and Her-2 statuses(P=2.15×10 -3 ; P=4.06×10 -3 , respectively). Interaction analysis showed that the three-loci model (rs3218438, rs3218536 and rs6964582) was the best with the maximal testing balance accuracy of 0.6597, and the maximal 100% cross-validation consistency (P=0.001). Conclusion: These results indicate that XRCC2 gene polymorphisms may affect the risk of breast cancer and show that some SNPs and haplotypes in XRCC2 are associated with breast cancer characteristics in the Han population of northwest China.