CYP1B1 and breast cancer: Although not significantly, the BC cases tend to have higher frequency of the CYP1A1 variant Val allele (57% in cases vs. 48% in controls), lower frequency of the CYP1B1 variant Val allele (9.7% in cases vs. 15% in controls), lower frequency of the CYP19 (C> T) variant T allele (13% vs. 18%) and lower frequency of the CYP19 (TTTA) ≥10 allele (6.5% vs. 14%).