ERBB2 and breast cancer: The inclusion and exclusion search of the literature resulted in a total of 18,125 relevant studies, and after excluding 18,115 studies according to the inclusion and exclusion criteria, we finally included three RCTs and seven single-arm clinical studies (Supplement Figure S1) that involved a total of 731 patients with HER2-positive breast cancer brain metastases who were treated with trastuzumab deruxtecan, trastuzumab emtansine, lapatinib neratinib, pyrotinib, pertuzumab, and trastuzumab anti-HER2 agents.