Although in comparison with CYP17 a smaller number of studies investigated the association of breast cancer with CYP19, findings for CYP19 have been more consistent, with most studies showing a positive association between CYP19 alleles with a higher number (10, 12, or 10 or more) of TTTA repeats and breast cancer [13,15-17]. Here, CYP17A1 is linked to breast cancer.