The Pharmaceutical Journal
Vol 278 No 7452 p575
19 May 2007

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Daily aspirin can prevent colorectal cancer but risks too high for general use

Taking 300mg or more of aspirin a day for five years can prevent colorectal cancer, according to research published in The Lancet (2007;369:1603). However, the author of an accompanying editorial (ibid, p1577) stresses that the potential risks of long-term aspirin use, and the availability of alternative strategies, such as screening, mean that widespread use of aspirin for cancer prevention cannot be recommended among the general population.

Researchers analysed data from two randomised controlled trials of aspirin (500mg and 300mg–1,200mg) versus placebo conducted in the late 1970s and early 1980s.

In a pooled analysis, taking aspirin was associated with a reduction in incidence of colorectal cancer (hazard ratio 0.74; 95 per cent confidence interval 0.56–0.97; P=0.02), which was greatest in those treated for five years or more and was only seen after a latency of at least 10 years.

The researchers also did a systematic review of observational studies, which yielded consistent associations between use of aspirin or other non-steroidal anti-inflammatory drugs and a reduced risk of colorectal cancer, but only when analyses were stratified by extent and duration of use. The effect was seen both in those with and those without a family history of the disease.

The researchers conclude that chemoprevention with aspirin might be cost-effective in certain high-risk groups, perhaps with risk-based screening.