ASPREE (ASPirin in Reducing Events in the Elderly)

19,114 participants followed for a median 4.7 years. Aspirin did not reduce disability-free survival (HR 1.01) or cardiovascular events, increased major haemorrhage (HR 1.38), and was associated with higher all-cause mortality (HR 1.14, 95% CI 1.01-1.29), driven by cancer deaths (HR 1.31, 95% CI 1.10-1.56), particularly from advanced or metastatic cancers. Extended follow-up did not show a later emergence of cancer prevention. The finding contradicts long-term follow-up of earlier aspirin trials in middle-aged adults and is unexplained; hypotheses include a different effect of aspirin on established late-life cancers. It was central to the US Preventive Services Task Force 2022 decision to withdraw the recommendation for aspirin to prevent colorectal cancer.