ERBB2 and breast cancer: <h4>Objective</h4>To assess the clinical value of the ALBI score and age in predicting trastuzumab resistance in patients with HER-2 positive breast cancer (BC).<h4>Methods</h4>A retrospective cohort study was conducted on patients with HER-2 positive BC treated with trastuzumab at the Department of Thyroid and Breast Surgery of Affiliated Hospital of Shandong University of Traditional Chinese Medicine from December 2017 to December 2023.