Aspirin: Is it Really a Wonder Drug?
Should aspirin be added to the water supply? This was the vision which sprang to mind last week when academics advised that the benefits of taking a small daily dose of aspirin far outweigh any side-effects for most healthy people aged 45 and over.
The pronouncement by a panel of experts speaking at the Royal Society of Medicine, comes a month after research from Oxford University, published in The Lancet, showed that taking 75mg of aspirin - a quarter of the standard over-the-counter pill - daily for five years reduces the risk of getting bowel cancer by a quarter, and deaths from the disease by a third. Research is expected to be published shortly showing similar effects for other cancers.
This simple painkiller has many well established benefits. It thins the blood, which is why it is routinely prescribed for people who already have heart disease or who have had a stroke. It is also often prescribed for people who may be at high risk of these illnesses - because of high blood pressure or diabetes, for example. And it's used widely for blood-clotting disorders and to help prevent recurrent miscarriage, migraines, cataracts, gum disease and pre-eclampsia (a serious complication of pregnancy).
But should low-dose aspirin now be taken daily by healthy people who want to stay that way? Is this a watershed in the history of public health medicine - a 'put it in the water' moment?
No is the simple answer, since it cannot be taken by certain people (including most children under 16). But Professor Gordon McVie, senior consultant at the European Institute of Oncology, Milan, is evangelical about the benefits of aspirin. 'For me this is clear cut,' he says. 'Aspirin is cheap and effective, and there is huge potential to cut the cases of illness particularly colon cancer.'
In agreement is Peter Elwood, Professor of Epidemiology at the University of Wales in Cardiff, who led the first randomised trial into the benefits of aspirin for heart disease patients in 1984 (and who has himself taken aspirin daily for the past ten years). 'Breakthrough is an overused word but in this case it is justified,' he says.' There is disagreement around the peripheral issues - how much to give, should there be an age range - but overall it seems clear to me that the latest work proves taking aspirin every day will increase your chance of survival against important diseases.'
The study which seems to have tipped the scales is principally the work of Oxford neurologist Professor Peter Rothwell (who has also started taking low-dose aspirin daily). He believes that aspirin's effect on bowel cancer is unlikely to be an isolated phenomenon, given the similarities in how cancers of different types develop. Last week he also advised that with the risk of cancer rising between 40 and 55, 45 would be an optimal age to start taking it.
Scientists have a theory as to why aspirin might be beneficial for human physiology. Professor McVie explains: 'It seems that around the time we developed an increased morbidity from heart diseases and stroke, natural salicylates (a plant hormone similar to the active ingredient in aspirin) disappeared from our diet. Most plants used to be stuffed with these but when we started growing foods using pesticides and fertilisers we also took out the salicylates - so perhaps it's a question of putting them back into food and restoring the balance in our bodies.'
But despite the excitement, not every doctor is reaching for the prescribing pad just yet.
For one thing, aspirin's usefulness in warding off heart attacks and strokes in healthy people is in doubt. The latest research, published in the Journal of the American Medical Association in March and involving almost 30,000 men and women, found it had no significant effect on heart attacks and strokes in low-risk populations.
And last year, the influential Drug and Therapeutics Bulletin (DTB), warned aspirin should not be used to prevent future heart attacks and strokes in people with no obvious sign of cardiovascular disease, as the risks outweigh any potential benefits.
The biggest drawback of taking aspirin is that it can irritate the lining of the stomach. Although for most people this side effect is mild, it can occasionally cause ulcers and in a small number of cases, serious bleeding, particularly in elderly people.
But what of the recent study on bowel cancer, the third most common cancer in Britain and which kills 600,000 people worldwide annually? Some doctors point out that while the study shows thousands of lives might indeed be saved by aspirin, the reduction in absolute risk of bowel cancer is about 1.5% (from 4% to 2.5%) .
Dr Ike Iheanacho, the DTB's editor, says that the reduction in risk is a 'sizeable benefit' from society's point of view.
'But one problem with this kind of data is that it's often reported as if the benefit to the individual is huge,' he says.
'In effect, around 60 people would have to take the aspirin continuously for around 5 years to prevent one death from bowel cancer during a 20-year period,' he says. 'While that remains a considerable benefit, it could clearly put a very different perspective on things for an individual deciding whether to take aspirin for this purpose.
'And this particular research didn't report adverse events related to aspirin. Let's not forget that the drug can cause major internal bleeding and this can kill. If you're going to advise people to take aspirin, you have to factor in potential harms to give them a balanced view of the potential effects of treatment.'
The blanket prescribing of any drug is also at odds with the 'stratified' response that most oncologists predict will be the future of cancer treatment - in other words, medical interventions will be tailored to our genetic makeup and our individual risk.
One way forward might be to give aspirin only to those at high risk of bowel cancer, an idea Professor McVie has said he supports; he believes that in a few years a blood test to detect those at higher risk will become available.
Overall, with medical opinion divided, the feeling is that the public will need to make up their own minds about whether to take low dose aspirin. Professor Peter Whorwell, a gastro-enterologist at Manchester University, advises that anyone considering taking it on a daily basis should discuss with their GP whether they also need to take drugs to protect the stomach.
Back to Professor McVie who with a family history of heart disease, confirms that he too has been taking aspirin daily for more than 20 years. 'I saw some data long before it was verified and published, and I was convinced,' he says. 'After this month's data, I'm pretty chuffed with myself now.'
Who shouldn't take aspirin?
• Aspirin should not be given to anyone under 16 unless under specialist advice. It can cause Reye's syndrome, a potentially fatal disease, in this age group
• Aspirin should be avoided if you have a stomach (peptic) ulcer, haemophilia or other bleeding disorder, or an allergy to aspirin or to other non-steroidal anti-inflammatory drugs (NSAID). These include ibuprofen and diclofenac
• Low-dose aspirin should only be taken with caution by certain groups, including those with asthma, allergies, liver, kidney or digestive problems.
• Pregnant and breastfeeding women should only take aspirin on the advice of a GP.
• Aspirin can interact with certain other medicines. Ask your doctor or pharmacist or read the patient information leaflet