Association Between XRCC5, 6 and 7 Gene Polymorphisms and the Risk of Breast Cancer: A HuGE Review and Meta-analysis

Objective: Non-homologous end joining (NHEJ) is a pathway for repairing DNA double-strand breaks.Recent publications indicated that XRCC5, XRCC6 and XRCC7 genes may participate in the pathogenesis ofbreast cancer. The aim of this Human Genome Epidemiology (HuGE) review and meta-analysis was to investigateassociations between XRCC5, XRCC6 and XRCC7 genetic polymorphisms in the NHEJ pathway and breastcancer risk.
Methods: Studies focusing on the relationship between genetic polymorphisms in XRCC5, XRCC6and XRCC7 genes and susceptibility to breast cancer were selected from the Pubmed, Cochrane library, Embase,Web of Science, Springerlink, CNKI and CBM databases. Data were extracted by two independent reviewers.The meta-analysis was performed with Review Manager Version 5.1.6 and STATA Version 12.0 software. Theodds ratio (OR) with 95% confidence interval (95%CI) was calculated based on the extracted data.
Results:According to the inclusion criteria, we final included seven studies with a total of 2,864 breast cancer cases and3,060 healthy controls. Meta-analysis results showed that rs3835 (G>A) and rs828907 (G>T) in XRCC5 gene,and rs132793 (G>A) in XRCC6 gene might increase the risk of breast cancer, while rs132788 G>T and rs6002421(A>G) might be protective factors. However, there was no relationship between XRCC7 genetic polymorphismsand the risk of breast cancer.
Conclusion: This meta-analysis suggests that the rs3835 G>A and rs828907 G>Tin XRCC5 gene, rs6002421 (A>G), rs132788 (G>T) and rs132793 (G>A) in XRCC6 gene might be risk factorsfor breast cancer, while the rs132788 (G>T) and rs6002421 (A>G) in XRCC6 gene might be protective.