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It鈥檚 hard to keep up with the latest advice on aspirin. Known for its powerful blood-thinning properties, it is routinely prescribed in low doses to people who have had a heart attack or stroke to protect them from having another.
This has prompted some to argue that it could have a preventive effect in people who have no history of heart problems too. In the US, an estimated 40 million adults now take aspirin every day.
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But last year, the US Food and Drug Administration warned against this practice, saying to help prevent heart disease, even those with a family history.
The key concern is a small but unquestionable risk of gastrointestinal bleeding and haemorrhagic stroke, caused by bleeding in the brain.
A study published in January found that out of 68,000 people in the US who had been prescribed aspirin for primary prevention 鈥� meaning they had a history of heart disease 鈥� one in 10 were inappropriately given the drug because their chances of heart attack or stroke were .
Now the humble painkiller is attracting attention for a different reason 鈥� its apparently remarkable effects on cancer prevention. Last year, a review of the evidence led by at Queen Mary University of London found that more than in the UK alone if all people aged 50 to 64 took a low-dose aspirin every day. Cuzick found that aspirin use led to a 30 per cent reduction in both the incidence and mortality of bowel, stomach and oesophageal cancer, with smaller effects on prostate, breast and lung cancer. The benefits took five years to kick in, but continued after stopping aspirin.
鈥淭he second most important thing you can do to prevent cancer, after not smoking, is to take a low-dose aspirin,鈥� says Cuzick. He expects NICE, the UK health advisory body, to review the data on aspirin and begin recommending it to the over-50s within two years.
The effect seems to be down to aspirin鈥檚 anti-inflammatory properties. Inflammation is part of the body鈥檚 natural reaction to an invader, but cancerous cells hijack it and use it to divide and spread.
Aspirin may also help because it reduces the number of platelets in the blood 鈥� platelets can shield cancerous cells in the bloodstream so they are not recognised by the immune system.
So how do you weigh up the risks?
鈥淲e estimate that there would be one serious bleeding event for every 300 people that took aspirin for 10 years,鈥� says Cuzick. 鈥淏ut aspirin would reduce eight deaths for every one that might be caused, so it鈥檚 a pretty strong case.鈥�
Cuzick found that to reap the benefits, adults would need to take a low dose-aspirin daily for five years 鈥� probably 10 鈥� between the ages of 50 and 65. However, after the age of 70, the risk of side effects increases, so at this point aspirin would be likely to do more harm than good.
Peter Elwood at Cardiff University School of Medicine, UK, says the risk of bleeds has been 鈥済rossly exaggerated鈥�. His research suggests they tend to occur when patients begin taking aspirin without being properly assessed for risk factors, such as high blood pressure or a history of stomach ulcers, so anyone thinking of taking aspirin regularly should consult their doctor first. And because ulcers are often caused by the common bacterium Helicobacter pylori, treating that first could protect against the side effects.
Read more: 鈥�Our daily pills: What everyday drugs are really doing to you鈥�
This article appeared in print under the headline 鈥淎spirin鈥�
