CYP19A1 and breast cancer: An aging world population with rising global burden of breast cancer [1], emerging evidence suggesting that postmenopausal obesity as well as weight gain over the adult years are positively associated with postmenopausal breast cancer [2] and the finding that breast cancer patients may have an inherently higher aromatase expression in breast adipose tissue when compared to healthy women [3] have increased research interest on mechanisms underlying aromatase action in breast carcinogenesis.