Great white hope

Recent headlines claiming a daily aspirin can cut the risk of cancer have made the budget painkiller look like David taking on the Goliath of major diseases.

Thanks to its clot-busting properties, aspirin already has a reputation for preventing heart attacks and strokes in people with existing cardiovascular disease. A series of recent studies has added to the evidence that it may also prevent cancer.

The latest research, reported by the American Cancer Society last month, linked daily aspirin use to a 16 per cent lower risk of death from cancer overall and a 40 per cent lower risk of bowel cancer, Australia's second-most-deadly cancer.

The chief executive officer of the Cancer Council Australia, Ian Olver, is the first to agree it is tantalising research, but his advice is to keep the lid on the aspirin bottle for now.

''It's incredibly interesting data but there are still a lot of unanswered questions, like what is the right dose, will it be as effective in people with a low or moderate risk of bowel cancer as it is in people with high risk of the disease, and how long should you take it for before it starts to work,'' he says.

Researchers from Oxford University studying the effect of low-dose aspirin (70 milligrams to 100 milligrams) on heart disease analysed the data to see if it had any effect on cancer. They found that daily aspirin intake was linked to a lower risk of developing cancer, as well as a lower risk of the disease spreading, and a lower risk of cancer death.

Another British study found daily aspirin halved the number of cancer cases in people with Lynch syndrome, an inherited condition that increases the risk of bowel cancer.

''An ongoing study is now looking at different doses of aspirin for people with Lynch syndrome and it may be that we're moving closer to where [aspirin is] recommended for people with a high risk of bowel cancer,'' Olver says. ''But for now it's best to talk to your doctor if you think your risk of the disease is higher.''

How aspirin might help protect against cancer is another unknown. One theory is that aspirin's anti-inflammatory effect may dampen low-grade inflammation that's thought to increase cancer risk.

''It's a case of 'watch this space' until we have more information to make a recommendation,'' Olver says.

The drug has a downside: it can increase the risk of bleeding in the stomach or the brain. A recent Italian study of more than 370,000 people found those taking low-dose aspirin were 55 per cent more likely to need hospital treatment for brain haemorrhage and gastrointestinal bleeding than those not.

''There's extremely strong evidence that aspirin can prevent a second heart attack or a stroke in people who've already had one event,'' says the clinical issues director of the Heart Foundation, Robert Grenfell. ''That's why we recommend aspirin to people who've had a heart attack or stroke unless they're allergic to aspirin or have a history of gastric bleeding … But for people with a low risk of cardiovascular disease, very large studies suggest that the benefit of preventing heart disease is too close to the risk of bleeding.

''There are some people who have a higher risk of a heart attack because they have high blood pressure, cholesterol or diabetes, and there's a suggestion that they may benefit from low-dose aspirin. It's a discussion to have with your GP, but the Heart Foundation isn't recommending it.''

Paula Goodyer blogs at smh.com.au/chewonthis

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