Single nucleotide polymorphisms in the homologous recombination repair genes and breast cancer risk in Polish women

Genetic polymorphisms in homologous recombination repair genes that can lead to protein haploinsufficiency are generally associated with increased cancer risk. The aim of the present study was to evaluate associations between the risk of breast cancer and single nucleotide polymorphisms in the genes, encoding three key proteins of the homologous recombination repair: RAD51 (the human homologue of the E. coli RecA protein), X-ray repair cross-complementing group (XRCC) 2 and XRCC3. The polymorphisms studied were G135C of the RAD51 gene (c. -98 G>C; rs1801320), Arg188His of the XRCC2 gene (c. 563 G>A; rs3218536), and Thr241Met of the XRCC3 gene (c. 722 C>T; rs861539). Each polymorphism was genotyped by the PCR-RFLP (restriction fragment-length polymorphism) method in 700 Polish female patients with sporadic breast cancer and in 708 cancer-free women, who served as controls. In the present study, we showed the association between RAD51 G135C polymorphism and the incidence of breast cancer (p < 0.0001), but found no significant association with XRCC2 Arg188His or XRCC3 Thr241Met polymorphism. Instead, significant association was identified between XRCC2 Arg188His or XRCC3 Thr241Met polymorphism and breast cancer progression, assessed by the histological grading. However, each of these three polymorphisms was not associated with the tumor size or the lymph node metastases. This study provides evidence that links single nucleotide polymorphisms of RAD51 and XRCC2/3 genes with the risk of breast cancer in Polish women. In conclusion, RAD51 G135C, XRCC2 Arg188His and XRCC3 Thr241Met polymorphisms may be regarded as predictive factors of sporadic breast cancer in female population.