Finally, when assessing the combined effects of both XRCC1 polymorphisms on breast cancer risk, women with 'low-risk' genotypes for both polymorphisms (Trp194 carriers and Gln399 non-carriers) had a 49% lower incidence of breast cancer than women with 'high-risk' genotypes for both polymorphisms (Trp194 non-carriers and Gln399 carriers; 95% CI 0.28 to 0.90). This evidence concerns the gene XRCC1 and breast cancer.