ESR1 and breast cancer: Similarly, Basile et al. reported that a high AR/ER ratio seems to be detrimental in BC treated with endocrine therapy (Basile et al., 2017), while in 2 validated BC cohorts, ER+ patients with AR positivity ≥78% had the best survival, and among them those with a ratio of AR: ERα >0.87 exhibited the best outcomes (Ricciardelli et al., 2018).