Aspirin cuts some cancer risk 60 percent

U. SOUTHAMPTON (UK) — Taking a regular dose of aspirin reduces the long-term risk of cancer by around 60 percent in people with a family history of the disease.

Evidence of the benefits of aspirin has been accumulating for more than 20 years, but new results published in The Lancet are the first from a randomized controlled trial.

Late last year an analysis of people who had taken part in the early aspirin trials to prevent heart attacks and strokes showed that in subsequent years they developed fewer cancers. The missing piece of the jigsaw was a randomized trial specifically looking at its effect on cancer.


“This landmark study provides good news for people with a genetic disposition to colon cancer because this is one of the first studies to show that aspirin can help proactively protect against development of this disease,” says Diana Eccles, professor at the University of Southampton.

The study involving scientists and clinicians from 43 centers in 16 countries followed nearly 1,000 patients, in some cases for more than 10 years.

The study focused on people with Lynch syndrome, an inherited genetic disorder which affects genes responsible for detecting and repairing damage in the DNA. Around half of these people develop cancer, mainly in the bowel and womb. Bowel cancer is the second commonest cause of cancer death in the UK, being responsible for 16,000 deaths a year.

Between 1999 and 2005 a total of 861 people began either taking two aspirin (600 mg) every day for two years or a placebo. At the end of the treatment stage in 2007 there was no difference between those who had taken aspirin and those who had not. However, the study team anticipated a longer term effect and designed the study for continued follow-up.

By 2010 there had been 19 new colorectal cancers among those who had received aspirin and 34 among those on placebo. The incidence of cancer among the group who had taken aspirin had halved—and the effect began to be seen five years after patients starting taking the aspirin.

A further analysis focused on the patients who took aspirin for at least two years and here the effects of aspirin were even more pronounced: a 63 percent reduced incidence of colorectal cancer was observed with 23 bowel cancers in the placebo group but only 10 in the aspirin group.

Looking at all cancers related to Lynch syndrome, including cancer of the endometrium or womb, almost 30 percent of the patients taking the placebo had developed a cancer compared to around 15 percent of those taking aspirin.

However, Professor John Burn from Newcastle University who led the international research collaboration stresses: “Before anyone begins to take aspirin on a regular basis they should consult their doctor as aspirin is known to bring with it a risk of stomach complaints including ulcers.”

The international team is now preparing a large-scale follow-up trial and is recruiting online for 3,000 people worldwide to test the effect of different doses of aspirin. The trial was overseen by Newcastle Hospitals NHS Foundation Trust and funded by the UK Medical Research Council, Cancer Research UK, the European Union and Bayer Pharma.

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