UK researchers believe that taking aspirin before cancer begins to develop, and for at least 10 years, could maximise the drug's potential to prevent cancer.
Previous studies have shown that patients who take aspirin are less likely to develop bowel and breast cancer. But regular aspirin use increases the risk of GI bleeding and stomach ulcers.
What is the research?
The findings are not based on any new research, but on a review of all currently available evidence.
The researchers examined 269 studies involving 79,102 patients suffering from a range of cancers, including colorectal, lung, breast and oesophagus.
A number of the studies showed that aspirin could reduce the risk of cancer.
The incidence of colorectal cancer was found to be 40 per cent lower in patients who were regularly taking aspirin than in those who did not take the drug.
What do the researchers say?
Lead researcher Professor Jack Cuzick, from the Cancer Research UK centre for epidemiology at Queen Mary, University of London, said: 'Taking aspirin regularly in your mid-forties could maximise the effect this drug has on preventing cancer.
'Taking aspirin at this age, which is about the time pre-cancerous lesions usually begin to develop, may be the best time to stop the disease from progressing to actual cancer.'
As the risks of serious side-effects of aspirin increase after 60 years old, taking long-term treatment before this age will help to minimise these side- effects, said Professor Cuzick.
For older patients who are already taking aspirin for cardiovascular disease, the drug may also provide additional protection against some cancers, he added.
What do other researchers say?
Ellen Mason, cardiac nurse at the British Heart Foundation, said: 'It is too early for cancer researchers to recommend taking aspirin to reduce the risk of cancer.
'Many thousands of people in the UK are prescribed aspirin because they have heart disease. This research does not prove that they will also get protection from cancer at a low dose, but as they already need to take aspirin it would be reassuring if further research eventually shows an anti-cancer benefit.'
- Taking aspirin in your forties was found to be optimal for reducing cancer risk and exposure to side-effects of the drug.
- Regular aspirin use can increase the risk of GI bleeding and stomach ulcers.