ESR1 and breast cancer: The first question on the pathology section concerned Ki67 testing, and 62% of the panelist endorsed the recommendations from the recent publication of the International Ki67 Breast Cancer Working Group [3], suggesting that in patients with estrogen receptor (ER) + human epidermal growth factor receptor-2 (HER2) − T1-2N0-1 BC, a tumour with a Ki67 < 5% would not warrant chemotherapy, while a Ki67 > 30% would justify chemotherapy.