CYP19A1 and ductal breast carcinoma in situ: Aromatase Inhibitors (AI) are more effective with a reduction of 50% of BC (IBIS-II, MAP3) and less toxic, but they are suitable only for postmenopausal women; this superiority of AI seems to appear also in DCIS (NSABP-B35 and IBIS-II (DCIS).