CYP19A1 and breast cancer: Furthermore, the possibility that the local E2 profile was influenced by aromatase-independent pathways involving the production of E1 from estrone sulfate or dehydroandrostenedione (DHEA) from DHEAS, and the conversion of E1 to E2 and DHEA to androstenediol by 17β-HSD1, as observed in hormone responsive primary breast cancer [53] and endometrial cancer [54], must be examined.