Thursday, 23 December 2010

Does long term aspirin prevent cancer? - Moayyedi & Jankowski detailed analysis

reposted from:
Jankowski wrote about the Peter Rothwell paper at Cancer Research UK.

The BMJ Editor wrote
Finally, aspirin. At the close of 2010, the Lancet published a meta-analysis of individual patient data from randomised controlled trials (Lancet 2010, doi:10.1016/S0140-6736(10)62110-1). It found a 21% reduction in deaths from cancer in people who took aspirin for almost six years. The news that aspirin prevented cancer hit the headlines, and no doubt prescriptions of aspirin in healthy people over a certain age are now on their way up. We asked Paul Moayyedi and Janusz Jankowski to look at the new data. In their editorial (doi:10.1136/bmj.c7326) they conclude that, with a number needed to treat of 200 but a 50% increased risk of serious gastrointestinal and extracranial bleeding, it is not clear that the benefits outweigh the risks, even when factoring in the cardioprotective effects of aspirin. Have a good, and rational, 2011.

BMJ 2010; 341:c7326 doi: 10.1136/bmj.c7326 (Published 22 December 2010)
Cite this as: BMJ 2010; 341:c7326
  • Editorial

  • Paul Moayyedi, professor of medicine1

  • Janusz A Jankowski, James Black fellow2

  • +Author Affiliations
    1. 11200 Main Street West, Hamilton, ON, Canada
    2. 2Division of Clinical Pharmacology, Department of Oncology, University of Oxford, Oxford OX3 7DQ, UK
    Potentially, but trials specifically designed to answer this question are needed
    The cardioprotective effects of aspirin are well established. A meta-analysis of individual subject data from primary prevention randomised controlled trials (RCTs) suggested that aspirin can reduce the relative risk of non-fatal myocardial infarction by about 20%. 1 Overall, however, the risks of treatment (severe gastrointestinal and extracranial bleeding) were roughly the same as the benefits, so routine use of aspirin as a primary preventive strategy was not recommended. The meta-analysis did not evaluate any potential reduction of mortality from cancer, as has been suggested by observational data. 2 Observational data are difficult to interpret, however, because associations may not be causal and may be the result of confounding or bias.3 Rothwell and colleagues have therefore conducted another meta-analysis of individual subject data from RCTs of aspirin versus no aspirin for prevention of vascular disease, but this time they evaluated mortality from cancer as the main outcome. 4 They found a 21% (95% confidence interval 8% to 32%) reduction in the odds of death from cancer in people who took aspirin for almost six years, and the effect was strongest for gastrointestinal cancers. The authors …

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