To mitigate confounding by indication bias, propensity score matching (PSM) and inverse probability of treatment weighting (IPTW) were applied.<h4>Results</h4>In total, 7258 patients with primary operable HER2-positive breast cancer were identified; 1789 (24.6%) received NAT and 5469 (75.4%), AT. Here, ERBB2 is linked to breast cancer.