At the phase III level, the LoTam trial (NCI 2024 06672) is testing tamoxifen 5 mg/day against standard endocrine therapies (tamoxifen 20 mg or aromatase inhibitors) in postmenopausal women with early-stage, molecularly low-risk breast cancer or a history of intraepithelial lesions. This evidence concerns the gene CYP19A1 and breast cancer.