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Can aspirin prevent cancer?

by Kat Arney | Analysis

2 May 2009

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Could aspirin prevent cancer?

Who will benefit from aspirin's cancer-preventing powers?

The humble over-the-counter drug aspirin hit the headlines this week, after the publication of a report led by a Cancer Research UK-funded scientist.

The researchers gathered together all the available evidence on cancer prevention, and concluded that there wasn’t enough evidence to make strong recommendations, particularly on aspirin dosage.  But  there was certainly a suggestion that taking aspirin in your forties could help prevent cancer later in life.

But how realistic is this? Should we all be popping aspirin as soon as we hit the big four-oh? Or do the risks outweigh the benefits?

We’ve previously written about aspirin’s apparent “wonder drug” powers, and discussed how it might work to prevent certain cancers.   And as well as its role in preventing cancer, the benefits of aspirin in cutting the risk of heart disease and stroke are well known. The NHS Choices blog has a great (and comprehensive) analysis of this week’s report, which was published in the journal Lancet Oncology,  but it’s worth highlighting a few key points.

Why is age important?
The review, led by Professor Jack Cuzick from the Cancer Research UK Centre for Epidemiology at Queen Mary, University of London, suggests that the best prevention strategy might be for people to take aspirin from their mid-forties for at least ten years.

This is because many cancers take years to grow – particularly in the case of bowel tumours – and often start while a person is in their late forties or early fifties.  So taking aspirin at this crucial age could lower the risk of tumours developing, or hinder their growth.

Another important reason is that aspirin causes side effects, including stomach ulcers and bleeding on the stomach and gut. These side effects get more common with age, and are much more likely to affect people in their 60s, compared with people in their 40s.

What types of cancer can aspirin prevent?
There’s good evidence that aspirin can help to prevent breast and bowel cancer – two of the UK’s most common cancers.  And there’s some evidence that it may have an impact on the risk of some other types of cancer, such as oesophageal cancer.

“So should I be taking aspirin?”
As with any medication – especially if it is taken over a long period of time – the risks and benefits of taking aspirin are something that should be discussed with a doctor.

Aspirin may seem like a harmless white tablet, but the side effects from long-term heavy usage can be significant, and need to be balanced against the potential benefits. And this is the key point of the Lancet Oncology report – we just don’t know what dose of aspirin will have the greatest cancer-prevention effect, balanced against the risk of side effects.

It’s likely that in the future, genetic studies will reveal who is most likely to benefit from taking aspirin for cancer prevention.  This will help doctors to tailor prevention strategies more accurately to suit an individual person, rather than the educated guesswork (for example, based on family history) that we rely on today.

What next?
The study’s authors conclude that there simply isn’t enough evidence to make hard and fast recommendations about who should be taking aspirin, how much and for how long.

More research is needed, such as large-scale trials testing the benefits of aspirin at different ages.  And more research also needs to be done into other drugs with similar effects, known as NSAIDs (non-steroidal anti-inflammatory drugs) that have fewer side effects than aspirin. But the publication of this report shows the scientific community is starting to look very seriously at whether aspirin could be used to prevent cancer in the future.


Watch a video of lead study author Professor Jack Cuzick explaining more about the report.



Cuzick, J., et al (2009). Aspirin and non-steroidal anti-inflammatory drugs for cancer prevention: an international consensus statement The Lancet Oncology, 10 (5), 501-507 DOI: 10.1016/S1470-2045(09)70035-X