More recently, the role of the androgen receptor as a tumour suppressor in AR+/ER+ breast tumours in vitro and in vivo has been described, suggesting that AR activation, not inhibition, may provide a therapeutic benefit [17], and this is currently being tested in ongoing clinical trials using AR agonists with encouraging findings (NCT01616758, NCT02463032). This evidence concerns the gene ESR1 and breast neoplasm.