Research News

Genetic marker may help target aspirin for colorectal cancer

BMJ 2012; 345 doi: http://dx.doi.org/10.1136/bmj.e7281 (Published 30 October 2012) Cite this as: BMJ 2012;345:e7281

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Researchers from the US have found a link between the use of aspirin and better survival in adults with a genetically distinct type of colorectal cancer. Among 161 men and women whose cancers had a mutation in the PIK3CA gene, use of aspirin after diagnosis was associated with a 46% reduction in all cause mortality (fully adjusted hazard ratio 0.54, 95% CI 0.31 to 0.94), and an even bigger drop in cancer related mortality (0.18, 0.06 to 0.61). Aspirin was not associated with mortality in 803 men and women with wild-type cancers.

Both groups came from much larger cohorts of health professionals, and these secondary analyses included only those with colorectal cancer who provided analysable tissue samples. Both cohorts had answered questions about use of aspirin every two years since recruitment.

We already have good evidence that aspirin slows the progression of colorectal cancer, says a linked editorial (p 1650). The new analyses add an intriguing twist. PIK3CA might be a useful genetic marker to help target adjuvant treatment with aspirin more effectively, but not yet. Just 66 patients with mutated cancers used aspirin after diagnosis, and only 18 of them died during follow-up (three from colorectal cancer). We now need bigger studies, done prospectively, to help guide practice.

If these associations are confirmed, genotyping colorectal cancers for PIK3CA could have a big impact on treatment with aspirin, says the editorial. About one in six colorectal cancers carries the mutation.

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Cite this as: BMJ 2012;345:e7281