The frequency of CYP1A1 Ile462Val was around 5% in breast cancer patients and 21% in healthy smokers, while the frequency of XRCC3 Met241Met was around 29% in breast cancer patients and 12% in healthy smokers, suggesting a possible interaction effect between CYP1A1 Ile462Val, XRCC3Thr241Met and risk of breast cancer in smokers, with regard to the risk for not developing breast cancer in smokers carrying the CYP1A1 Ile462Val genotype after interaction logistic regression analysis (p < 0.001, OR = 7.57 (2.48–23.25)). Here, XRCC3 is linked to breast cancer.