Effect of daily aspirin on long-term risk of death due to cancer: analysis of individual patient data from randomised trials.

Abstract (PubMed)

Treatment with daily aspirin for 5 years or longer reduces subsequent risk of colorectal cancer. Several lines of evidence suggest that aspirin might also reduce risk of other cancers, particularly of the gastrointestinal tract, but proof in man is lacking. We studied deaths due to cancer during and after randomised trials of daily aspirin versus control done originally for prevention of vascular events. We used individual patient data from all randomised trials of daily aspirin versus no aspirin with mean duration of scheduled trial treatment of 4 years or longer to determine the effect of allocation to aspirin on risk of cancer death in relation to scheduled duration of trial treatment for gastrointestinal and non-gastrointestinal cancers. In three large UK trials, long-term post-trial follow-up of individual patients was obtained from death certificates and cancer registries. In eight eligible trials (25,570 patients, 674 cancer deaths), allocation to aspirin reduced death due to cancer (pooled odds ratio 0.79, 95% CI 0.68-0.92, p=0.003) after 20 years of follow-up. The latent period before any effect on deaths was 5 years for oesophageal, pancreatic, brain, and lung cancer, but was more delayed (10 years) for stomach, colorectal, and prostate cancer. FUNDING: None.