Larger studies are needed to confirm our initial findings, however, our results provide evidence that the main effect of CYP1A1 in estrogenic metabolism rather than in tobacco carcinogen activation in breast cancer patients and also confirmed the hypothesis that CYP1A1 Ile462Val, in association with long periods of active smoking, could be a breast cancer risk factor. This evidence concerns the gene CYP1A1 and breast carcinoma.