21 March 2012 Last updated at 00:33 GMT
Daily aspirin 'prevents and possibly treats cancer'
By Michelle Roberts
Health reporter, BBC News
Taking a low dose of aspirin every day can prevent and possibly even treat cancer, fresh evidence suggests.
The three new studies published by The Lancet add to mounting evidence of the drug's anti-cancer effects.
Many people already take daily aspirin as a heart drug.
But experts warn that there is still not enough proof to recommend it to prevent cancer cases and deaths and warn that the drug can cause dangerous side effects like stomach bleeds.
Prof Peter Rothwell, from Oxford University, and colleagues, who carried out the latest work, had already linked aspirin with a lower risk of certain cancers, particularly bowel cancer.
But their previous work suggested people needed to take the drug for about 10 years to get any protection.
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Aspirin (acetylsalicylic acid) has been used for many years as a painkiller. It has an anti-inflammatory action
Low-dose (75mg) aspirin is already recommended for people with known cardiovascular disease to prevent stroke and heart attack
The benefits for healthy people are still unclear
Aspirin can cause fatal internal bleeding, although this is relatively rare
Now the same experts believe the protective effect occurs much sooner - within three to five years - based on a new analysis of data from 51 trials involving more than 77,000 patients.
And aspirin appears not only to reduce the risk of developing many different cancers in the first place, but may also stop cancers spreading around the body.
The trials were designed to compare aspirin with no treatment for the prevention of heart disease.
But when Prof Rothwell's team examined how many of the participants developed and died from cancer, they found this was also related to aspirin use.
Halting cancer spread
Taking a low (75-300mg) daily dose of the drug appeared to cut the total number of cancer cases by about a quarter after only three years - there were nine cancer cases per 1,000 each year in the aspirin-taking group, compared with 12 per 1,000 for those taking dummy pills.
It also reduced the risk of a cancer death by 15% within five years (and sooner if the dose was higher than 300mg)
And if patients stayed on aspirin for longer, their cancer death risk went down even further - by 37% after five years.
Low-dose aspirin also appeared to reduce the likelihood that cancers, particularly bowel, would spread (metastasise) to other parts of the body, and by as much as half in some instances.
In absolute numbers, this could mean for every five patients treated with aspirin one metastatic cancer would be prevented, the researchers estimate.
At the same time, aspirin cut the risk of heart attacks and strokes, but it also increased the risk of a major bleed.
However this elevated bleeding risk was only seen in the first few years of aspirin therapy and decreased after that.
Critics point out that some of the doses given in the study were much higher than the 75mg dose typically given in the UK. Also, some very large US studies looking at aspirin use were not included in the analysis. The researchers acknowledge both of these points in their published papers.
Prof Rothwell says for most fit and healthy people, the most important things they can do to reduce their lifetime cancer risk is to give up smoking, take exercise and have a healthy diet.
After that aspirin does seem to reduce the risk further - only by a small amount if there is no risk factor, but if there is a family history for something like colorectal cancer, it tips the balance in favour of aspirin, he said.
Prof Peter Johnson, of Cancer Research UK, said it was still a good idea for people thinking of taking aspirin to discuss it with their GP because of the possible side effects.
But he said the work was exciting and suggested aspirin might be beneficial for treating and preventing cancer, which is something the charity is exploring in its own research.
"We now need some definitive advice from the government as to whether aspirin should be recommended more widely," he said.
The National Institute for Health and Clinical Excellence (Nice), which issues treatment guidelines for the NHS, has not yet been asked by the government to look at the topic but a spokesman for the Department of Health said they were considering how best to advise the public about the benefits and risks of aspirin.
Studies find an aspirin a day can keep cancer at bay
By Kate Kelland
LONDON | Tue Mar 20, 2012 9:17pm EDT
(Reuters) - Three new studies published on Wednesday added to growing scientific evidence suggesting that taking a daily dose of aspirin can help prevent, and possibly treat, cancer.
Previous studies have found that daily aspirin reduces the long-term risk of death due to cancer, but until now the shorter-term effects have been less certain - as has the medicine's potential in patients already diagnosed with cancer.
The new studies, led by Peter Rothwell of Britain's Oxford University, found that aspirin also has a short-term benefit in preventing cancer, and that it reduces the likelihood that cancers will spread to other organs by about 40 to 50 percent.
"These findings add to the case for use of aspirin to prevent cancer, particularly if people are at increased risk," Rothwell said.
"Perhaps more importantly, they also raise the distinct possibility that aspirin will be effective as an additional treatment for cancer - to prevent distant spread of the disease."
This was particularly important because it is the process of spread of cancer, or "metastasis", which most often kills people with the disease, he added.
Aspirin, originally developed by Bayer, is a cheap over-the-counter drug generally used to combat pain or reduce fever.
The drug reduces the risk of clots forming in blood vessels and can therefore protect against heart attacks and strokes, so it is often prescribed for people who already suffer with heart disease and have already had one or several attacks.
Aspirin also increases the risk of bleeding in the stomach to around one patient in every thousand per year, a factor which has fuelled an intense debate about whether doctors should advise patients to take it as regularly as every day.
Last year, a study by British researchers questioned the wisdom of daily aspirin for reducing the risk of early death from a heart attack or stroke because they said the increased risk of internal bleeding outweighed the potential benefit.
Other studies, including some by Rothwell in 2007, 2010 and 2011, found that an aspirin a day, even at a low dose of around 75 milligrams, reduces the long-term risk of developing some cancers, particularly bowel and oesophageal cancer, but the effects don't show until eight to 10 years after the start of treatment.
Rothwell, whose new studies were published in The Lancet and The Lancet Oncology journals on Wednesday, said this delay was because aspirin was preventing the very early development of cancers and there was a long time lag between this stage and a patient having clinical signs or symptoms of cancer.
Rothwell and others said deeper research was now needed into aspirin as a potential treatment for cancer in patients whose disease has not yet spread.
"No drug has been shown before to prevent distant metastasis and so these findings should focus future research on this crucial aspect of treatment," he said.
Peter Johnson, chief clinician at the charity Cancer Research UK, said his group was already investigating the anti-cancer properties of aspirin. "These findings show we're on the right track," he said.
In a written commentary on the research in The Lancet, Andrew Chan and Nancy Cook of Harvard Medical School in the United States said it was "impressive" and moved health experts "another step closer to broadening recommendations for aspirin use".
(Reporting by Kate Kelland; Editing by Susan Fenton)
The Lancet, Early Online Publication, 21 March 2012
doi:10.1016/S0140-6736(11)61654-1Cite or Link Using DOI
Are we ready to recommend aspirin for cancer prevention?
Andrew T Chan a, Nancy R Cook b
In The Lancet , Peter Rothwell and colleagues 1 report additional data supporting the hope that daily aspirin can ward off a panoply of cancers. Aspirin's role in reducing risk of vascular events is well established, although which risk factor profiles derive net benefit remain controversial. 2 The strongest proof of aspirin's antineoplastic effect has been in colorectal tumours. Several epidemiological studies, 3 randomised controlled trials of colon polyp recurrence, 4 and randomised trials in patients ...
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