We prospectively collected data from patients with HER-2 positive breast cancer (less than 1 cm and node negative) patients who underwent breast cancer surgery at Shanxi Provincial People's Hospital Breast Center from January 1, 2017 to December 31, 2019, and retrospectively investigated the association between baseline clinicopathological features and treatment strategy, cardiotoxicity, and disease outcome. Here, ERBB2 is linked to breast cancer.