Results of a study published Friday in The Lancet suggested that taking a daily dose of aspirin can reduce the risk of people with Lynch syndrome developing colorectal cancer by more than 60 percent.

Earlier research had indicated such an effect, but the CAPP2 trial, which was partly funded by Bayer, was the first designed to specifically investigate the prevention of colorectal cancer as its main goal.

The study randomised 861 people with Lynch syndrome, a genetic condition that predisposes a person to developing certain cancers, to receive 600 milligrams of aspirin or placebo daily for up to four years. An initial analysis in 2007 found that there was no difference in cancer rates between the two groups.

However, the new analysis showed that at an average follow-up of 55.7 months, 18 of the 427 people who took aspirin had developed colorectal cancer, compared to 30 of 434 people who received placebo.

Further, among those subjects who adhered to the treatment schedule for two years, 10 cases of colorectal cancer were seen in the 258 people who took aspirin, versus 23 cases of the disease in 250 people who were given placebo. The researchers noted that the result represented a 63-percent reduction in the risk of colorectal cancer between the two groups. Rates of side effects were similar in both groups.

Study leader John Burn noted that similar results were found for endometrial and uterine tumours stemming from Lynch syndrome in favour of people who took aspirin. Data showed that 38 people in the study developed tumours at sites other than the bowel, 16 of whom took aspirin. The researchers reported that five people in the aspirin group developed endometrial cancer, compared with 13 who took placebo.

"What we have finally shown is that aspirin has a major preventative effect on cancer but this doesn't become apparent until years later," Burn said. "What surprised us was that there was no difference in the number of people developing polyps, which are thought to be the precursors of cancer," remarked Tim Bishop, who led the statistical analysis of the data. "But many fewer patients who had been taking aspirin years before went on to develop cancers," Bishop noted.

Burn estimated that if the approximately 30 000 people with Lynch syndrome in the UK were to start taking daily aspirin then some 10 000 cancers would be prevented over the next 30 years, saving around 1000 lives.

However, he noted that an additional 1000 people would develop stomach ulcers as a result of taking the drug. "There's a trade-off. If we could get by on a smaller dose, then we could potentially avoid a lot of those ulcers," Burn commented.

A follow-up five-year trial is expected to compare the effects of different doses of aspirin in approximately 3000 people with Lynch syndrome in order to determine optimal dosing. The researchers noted that it is not yet clear how aspirin works to prevent colorectal cancer, but Burn said that the delayed effect suggested that the compound may target faulty stem cells before they mutate into pre-cancerous cells.

 

 

Ref: BBC News, BusinessWeek, The Lancet, The Telegraph, MSNBC, London South East, USA Today, The Daily Mirror, The Guardian)