An aspirin a day can keep bowel cancer away, a new study has shown.
Researchers found taking a daily dose of 300mg or more of aspirin for five years can prevent colorectal cancer later in life.
Incidence of bowel cancer was reduced by up to 74 per cent in the subsequent ten to 15 years after the treatment was started.
The cancer typically takes at least 10 years to develop from pre-cancerous growths in the gut.
Except in special circumstances, doctors generally advise against long-term aspirin use because of the risk of serious side effects such as internal bleeding and stomach ulcers.
But the authors of the new study, reported today in The Lancet medical journal, say in the case of people with a higher-than-average risk of bowel cancer the benefits may outweigh the risks.
Each year, around 35,000 men and women in the UK are diagnosed with bowel cancer, and more than 16,000 die from the disease.
The new research, led by Professor Peter Rothwell from Radcliffe Infirmary, Oxford, revisited patients from two large aspirin trials conducted in the late 1970s and early 1980s.
The aim was to see if regularly taking aspirin had any delayed effect on bowel cancer rates.
Using aspirin for five years was found to reduce the subsequent incidence of bowel cancer by 37 per cent overall, and 74 per cent during the period 10 to 15 years after the trials started.
An accompanying review of 30 observational studies suggested that taking medium-to-high doses of aspirin for 10 years or more reduced the risk of developing the disease by 50 -70 per cent.
The protective effect of aspirin appeared to be consistent regardless of age, sex, race or country of origin. It was also seen in individuals who had a close family relative with bowel cancer, which normally raises the lifetime risk by two to four times.
In an accompanying comment, American expert Dr Andrew Chan, from Massachusetts General Hospital in Boston, said the findings were ‘convincing evidence’ that aspirin can reduce the incidence of bowel cancer.
But he added: ‘However, with the concerns about the potential risks of long-term aspirin use and the availability of alternative prevention strategies (e.g. screening), these findings are not sufficient to warrant a recommendation for the general population to use aspirin for cancer prevention.’
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