Anti-thrombotic therapy (ATT) in cancer patients approaching the end of life presents significant clinical challenges, balancing thrombotic and bleeding risks. This study analysed ATT prescribing patterns and associated outcomes in patients diagnosed with poor prognosis cancer, defined as cancer diagnoses associated with a 1-year life expectancy, using the Welsh national Secure Anonymised Information Linkage Databank. Retrospective cohort study of adults in Wales diagnosed with poor prognosis cancer between 2013 and 2021, following up patients from cancer diagnosis until death, end of follow-up or study end (31 December 2021). Outcomes included ATT discontinuation, bleeding and thromboembolic events in secondary care. We identified a cohort of 25 783 adults with a median survival of 145 days. Of these, 32% were receiving ATT at diagnosis, with 77% continuing until death. One-year cumulative incidence of ATT discontinuation was 19% (95% CI: 18%-20%). The 1-year cumulative incidence of bleeding was 3.2% (95% CI: 3.0%-3.4%) and of thromboembolic events was 5.3% (95% CI: 5.0%-5.6%). ATT was prevalent at cancer diagnosis and discontinuation before death was uncommon. The management of ATT is complex in patients with advanced cancer and there is a need for clearer guidance on appropriate discontinuation strategies as well as when to continue these medicines.

© 2025 The Author(s). British Journal of Haematology published by British Society for Haematology and John Wiley & Sons Ltd.