RESUMO
BACKGROUND: Thanks to immense improvements in technology over the past few decades, we have witnessed a major shift towards the idea that breast cancer results from a combined effect of multiple common alleles conferring low risk. This study investigates the role of 3 nonsynonymous SNPs in the DNA repair genes XRCC1 (R399Q), RAD51 (G135C) and TP53 (Arg72Pro) in breast cancer in Serbian women. PATIENTS AND METHODS: Cases of BRCA1/2-negative hereditary breast cancer (n = 52), sporadic breast cancer (n = 106) and age-matched cancer-free female controls (n = 104) were obtained from the Institute for Oncology and Radiology of Serbia's blood bank. Restriction fragment length polymorphism analysis was used for genotyping. Descriptive analyses included genotype and allelic frequencies; the odds ratio and 95% confidence interval were calculated as an estimate of the relative risk. RESULTS: A significant difference in QQ+RQ versus RR genotype distribution of XRCC1 was observed between hereditary breast cancer patients and cancer-free controls. The association was confirmed among young breast cancer patients from these high-risk families. The existence of 3 recessive alleles in the RAD51 and XRCC1 genotype combination showed an association with hereditary breast cancer. Odds ratio analysis indicated a strong protective role of the RAD51 GG + TP53 ArgArg + XRCC1 RR combined genotype against hereditary breast cancer negative for BRCA1/2 mutations. CONCLUSIONS: The XRCC1 R399Q polymorphism showed an association with increased breast cancer risk in Serbia, especially in the hereditary form of the disease and in young breast cancer patients. Dominant alleles of RAD51, TP53 and XRCC1 combined genotypes indicated a strong protective role against hereditary breast cancer.