ESR1 and breast cancer: Numerous studies have reported that approximately 80% of breast cancers are positive for AR, furthermore AR protein is detectable across luminal A (ERα+ve, PR+ve, Her2-ve), Luminal B (ERα+ve, PR+ve, Her2+ve), triple-negative/basal (ER-ve, PR-ve and Her2-ve) and Her2 amplified (Her2+) (13, 44).