Introduction
The management of HER2-positive metastatic breast cancer (HER2+ mBC) has undergone significant evolution over recent years, primarily driven by the development of targeted therapies that improve survival outcomes. Traditionally, trastuzumab emtansine (T-DM1) has been a cornerstone in the second-line setting, while newer agents like trastuzumab deruxtecan (T-DXd) and tucatinib have expanded therapeutic options, especially for later lines of treatment. Despite promising results from clinical trials, real-world evidence (RWE) is crucial to validate these findings across diverse patient populations, guiding clinicians on optimal treatment sequencing and safety management.
