ESR1 and breast cancer: PIK3CA‐mutated breast cancer can be treated with the PI3Kα‐specific inhibitor alpelisib, which has been approved by the United States Food and Drug Administration (US FDA) for ER(+)/HER2(−) advanced disease [39]; patients with germline BRCA1/2 mutations benefit from poly(ADP‐ribose) polymerase (PARP) inhibitors such as olaparib or talazoparib [40].