Abstract Background Various breast cancer (BC) treatments, such as chemotherapy and targeted therapies, increase cardiotoxicity-risk and lead to premature ischemic heart disease and heart failure among survivors. Reducing this adverse risk through early recognition and (preventive) treatment is therefore important. Conversely, we feel that screening for cardiotoxicity is currently insufficiently standardized in daily practice. A fundamental first step in identifying areas of improvement is providing an overview of current practice. Objective This study aims to describe current cardiac surveillance for women with BC during and after cardiotoxic cancer treatment, using routinely collected hospital data in the Netherlands. The study also describes hospital variation in cardiac surveillance. Methods This observational study was performed on claims data provided by Statistics Netherlands. From the data, newly diagnosed BC patients in 2013 (N = 16,040) were selected and followed up until 2015. Healthcare ...