ESR1 and breast cancer: In June 2021, these data prompted the update of the NCCN guidelines that now recommended 1 year of intensive adjuvant therapy with olaparib for ER+/HER2- early BC with BRCA1/2m and residual disease and a CPS + EG score ≥ 3 in the case of previous neoadjuvant chemotherapy or ≥ 4 positive lymph nodes after the initial surgery.