Older patients with HER2-positive metastatic breast (HER2 + MBC) cancer are underrepresented in clinical trials. We aim to describe the treatment patterns and overall survival (OS) for older women receiving trastuzumab for HER2 + MBC. | Trastuzumab use in older patients with HER2-positive metastatic breast cancer Outcomes and treatment patterns in a whole-of-population Australian cohort 2003 2015