ERBB2 and breast cancer: This study included 5390 HR-positive/HER2-positive BC patients (of whom 2410 in premenopausal status) from 6 randomized trials: five trials of adjuvant ET (TEAM, ATAC, BIG 1–98, TEXT, and SOFT) and one trial of adjuvant anti-HER2-therapy (ALTTO)26.