ERBB2 and breast cancer: To investigate the relationship between the TP53 signature and the clinical outcomes after NAC in HrR+ and HER2− (HrR+/HER2−) breast cancer, we compared RFS and OS between patients with HrR+/HER2− in the NAC cohort [NAC (HrR+/HER2−)] and patients with HER2− in the PC-naïve_HrR+ cohort [PC-naïve (HrR+/HER2−)].