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Aspirin associated with reduced risk of cancer

Long-term aspirin treatment is associated with a reduced risk of cancer and should be considered for primary prevention of malignancy, say UK researchers.

In data that supports previous studies that have shown a positive effect on non-vascular death, UK researchers looked at 34 trials and found a 25% reduction in deaths from cancer in patients taking aspirin, compared to those who were not.

The findings come after a number of studies cast doubt on the use of aspirin for the primary prevention of cardiovascular events, and show the vascular benefits reduced over time, but a reduction in cancer incidence persisted.

In the biggest analysis of the benefits and risks of aspirin to date, researchers analysed data from 70,000 patients recruited to randomised trials of daily aspirin versus no aspirin, and found those taking aspirin had a reduced rate of cancer incidence from three years onwards.

There was a 24% reduction in risk of cancer in women and a 25% reduction in men taking aspirin, compared with those who were not.

The reduced risk of major vascular events with aspirin was initially offset by an increased risk of major bleeding, but effects diminished with increasing follow-up, leaving an absolute reduction of 3.13 per 1,000 patients per year from three years onwards compared with those not taking aspirin.

Two other studies - published in the Lancet journal and Lancet Oncology today – showed the mechanism of action could be in preventing distant metastasis of cancers.

Study leader Professor Peter Rothwell, professor of neurology at the University of Oxford, said: ‘In view of the very low rates of vascular events in recent and ongoing trials of aspirin in primary prevention, prevention of cancer could become the main justification for aspirin use in this setting.'

An editorial from Professor Andrew Chan, assistant professor of medicine at Massachusetts General Hospital, and Professor Nancy Cook, associate professor at Harvard Medical School, said the study results were ‘compelling' but warned more data on the bleeding risk with aspirin was needed.

‘Rothwell and colleagues' impressive collection of data moves us another step closer to broadening recommendations for aspirin use,' they said.

‘Moreover, future evidence-based guidelines for aspirin prophylaxis can no longer consider the use of aspirin for the prevention of vascular disease in isolation from cancer prevention.'

Glasgow GP Dr Margaret McCartney, in her critique of the study, said: 'The effect on all cause mortality was not significant. Rather a lot of people need to be treated with aspirin to prevent cancer, and we don't know that this will reduce overall death rates.'


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