Increasing awareness of the elevated risk of cardiovascular disease after breast cancer prompted a major recent statement from the American Heart Association, highlighting the need for better evidence on the topic, and better evidence-based care to mitigate the raised risks. Long-term cardiotoxicities of anti-cancer therapies are increasingly recognised as a major factor leading to the higher incidence of specific cardiovascular diseases in breast cancer survivors. The best-characterised effects are for older drugs (e.g. anthracyclines), but much of the evidence dates back to eras with different dosing, treatment paradigms and technologies. The postulated effects of newer therapies and regimens are based on limited evidence. Furthermore, how real-world treatment combinations translate to cardiovascular disease incidence in the growing survivor population is unclear [5]. The aim of this project will be to fully understand the effect of endocrine therapies on a range of cardiovascular outcomes.