The most recent ASPREE report (1) can be set in broader context.  A systematic review and meta-analysis of primary prevention trials, which included ASPREE, found aspirin gave a non-significant reduction of all-cause mortality by 3% (relative risk 0.97, 95% confidence interval 0.93-1.01).  The problem with all trials, however, is treatment contamination which in the case of aspirin could be very important.

For patients randomised to aspirin, there is firstly the problem of non-compliance which will inevitably erode any benefits.  One might argue that this would also erode the risks of aspirin yet in all-cause mortality, there is no valid evidence bleeds from aspirin are fatal (3).  There is another problem with those who take aspirin and then stop, namely the rebound risks of vascular events (4) with some likely to be fatal.

As for those randomised to placebo, some may self-medicate with aspirin as an easily available medicine.  This will further erode the measured benefit as the placebo arm will be inflated by those taking aspirin.  Given that all-cause mortality is so close to reaching statistical significance in all primary prevention trials combined, the probability of eroded benefit suggests that aspirin may reduce the risk of death.

Even a small effect on all-cause mortality from aspirin could have a big public health benefit if taken widely in the general community in those without contraindications.  It may be part of healthy ageing delivered via bowel cancer screening in individuals starting at 50 years old (5).          

1. Orchard SG et al. Cancer Incidence and Mortality With Aspirin in Older Adults: Follow-Up of the ASPREE Trial. JAMA Oncol. 2026;12(3):285–294. doi:10.1001/jamaoncol.2025.6196

2. Laferrière C et al, Aspirin for the Primary Prevention of Vascular Ischemic Events: An Updated Systematic Review and Meta-analysis to Support Shared Decision-Making. CJC Open. 2023 Aug 30;5(12):881-890. doi: 10.1016/j.cjco.2023.08.011.

3. Elwood PC, et al. Systematic Review and Meta-Analysis of Randomised Trials to Ascertain Fatal Gastrointestinal Bleeding Events Attributable to Preventive Low-Dose Aspirin: No Evidence of Increased Risk. PLoS One. 2016 Nov 15;11(11):e0166166. doi: 10.1371/journal.pone.0166166.

4. Zeitouni M, Montalescot G. Heart-breaking aspirin interruption. J Thorac Dis. 2018 Jan;10(1):30-34. doi: 10.21037/jtd.2017.12.42. 5.

5. Morgan G.  Aspirin for the primary prevention of bowel cancer in the population: A cost-effective balance of benefit and risk? https://ecancer.org/en/news/27855-aspirin-not-a-quick-fix-for-preventing-bowel-cancer-cochrane-review