Acetylsalicylic acid is one of the most widely taken medicines in the world. It is used to reduce fever and pain, and more recently to help prevent cardiovascular disease due to its anti-clotting effects. A new study suggests acetylsalicylic acid may also have a protective effect against some forms of cancer.
Acetylsalicylic acid reduces the risk of stroke and heart attack
The use of daily low-dose acetylsalicylic acid in patients with known cardiovascular disease is well established. Acetylsalicylic acid has anti-clotting effects through its inhibition of the production of prostaglandins by platelets (Roth and Calverley, 1994). Acetylsalicylic acid may also be recommended in patients considered at risk of developing cardiovascular disease, although this is more controversial (Hayden et al, 2002).
New study suggests daily acetylsalicylic acidmay reduce risk of cancer
It has been suggested for some time on the basis of observational studies that daily low-dose acetylsalicylic acid may protect against the development of some forms of cancer. Acetylsalicylic acid has been shown to reduce incidence or growth rate of cancer in animal models, and this is believed to be at least in part due to its inhibition of the production of prostaglandins and other inflammatory mediators. However, it is not clear whether this effect is applicable to human cancers.
Previous follow-up studies of randomised trials have so far failed to confirm a link between the use of low-dose acetylsalicylic acid and the risk of developing cancer. Rothwell et al (2010) believe that in order to benefit from a significant degree of cancer protection, patients need to take daily acetylsalicylic acid doses for a minimum period of 5 years. Prior studies have looked at shorter trial periods or fewer doses, and this could be why they failed to identify a protective effect.
The new study by Rothwell et al is a meta-analysis utilising records from previous randomised studies involving long-term daily doses of acetylsalicylic acid. The study combined the results of eight eligible trials, using data from over 25 000 patients, from which there were 674 cancer deaths. The researchers found that daily use of acetylsalicylic acid reduced the risk of death due to cancer by about 20% compared with the control group. This effect was limited to certain cancers, in particular adenocarcinomas.
Long-term use of acetylsalicylic acid has side-effects
Although a daily low dose of acetylsalicylic acid is considered on balance to be beneficial for certain groups of patients at risk from stroke or cardiovascular disease, there is a significant risk of adverse effects associated with this treatment regime. The risk of major bleeding and major gastrointestinal bleeding are both estimated at around 1 person for every 800 taking low-dose acetylsalicylic acid per year, and the risk of intracranial bleeding is much lower (NHS Clinical Knowledge Summaries).
This new study suggests that daily acetylsalicylic acid may reduce the risk of premature death due to cancer and cardiovascular conditions, however the public are urged not to take acetylsalicylic acid on a regular basis without first consulting their doctor. As Professor Peter Rothwell pointed out in an interview for BBC Television, “the balance of risk and benefit is relatively fine in people who don’t have risk factors for heart attacks and strokes”.
Sources
GJ Roth, DC Calverley “Aspirin, Platelets and Thrombosis: Theory and Practice” Blood 83:885-898 (1994)
M Hayden, M Pignone, C Phillips “Aspirin for the Primary Prevention of Cardiovascular Events: A summary of the Evidence for the US Preventative Services Task Force” Annals of Internal Medicine 136:161-172 (2002)
PM Rothwell, FGR Fowkes, JFF Belch “Effect of Daily Aspirin on Long-Term Risk of Death Due to Cancer: Analysis of Individual Patient Data from Randomised Trials” The Lancet Early Online Publication doi:10.1016/S0140-6736(10)62110-1 (2010)
“Evidence on the Adverse Effects of Aspirin and Clopidogrel” NHS Clinical Knowledge Summaries (2006)
Disclaimer: The information contained in this article is for educational purposes only and should not be used for diagnosis or to guide treatment without the opinion of a health professional. Any reader who is concerned about his or her health should contact a doctor for advice.
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Veronica Mitchell - Veronica studied veterinary medicine at Cambridge University before becoming a secondary school science teacher. She enjoys writing about ...
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