AR and breast cancer: In the study of Cochrane et al., in a cohort of 192 ER + breast cancer women, it was seen that a high AR/ER ratio (≥2.0) increased the risk of failure more than fourfold while using tamoxifen; the researchers stated that a high AR/ER ratio may negatively affect the response to endocrine therapy in breast cancer, and that AR may activate protumorigenic pathways in breast cancers in the absence of estrogen in a postmenopausal patient receiving AI treatment [25].