While we were not able to examine the effects of different types of ET (e.g., aromatase inhibitors vs. TAM) on outcomes from DCIS in the real-world setting, results from the RCTs indicate that anastrozole may be superior to TAM in postmenopausal women younger than 60 years (NSABP B-35 trial) [84], or at least non-inferior (International Breast Cancer Intervention Study-II (IBIS-II) trial [85]). Here, CYP19A1 is linked to ductal breast carcinoma in situ.