HER2-low expression consisted of 80.27% and 60.00% in the HR-positive/HER2-negative cohort and triple-negative cohort for primary breast cancer, respectively, and 74.14% and 53.23% in the HR-positive/HER2-negative cohort and triple-negative cohort for residual breast cancer after NAT, respectively. Here, ERBB2 is linked to breast cancer.