Does aspirin really reduce the risk of colon cancer? Authors' reply

摘要

We are grateful to John Cleland for his thoughtful response to our article, but nothing in his letter changes our conclusions. The planned primary analysis of the CAPP2 study-ie, the effect of 600 mg aspirin per day for 2 years on colorectal cancer in carriers of Lynch syndrome-is in the paper in The Lancet.1 The 2008 paper, based on exit colonoscopy data at the end of intervention, examined the secondary endpoint of the effect of aspirin on adenoma formation. We were surprised by the complete lack of effect on adenoma formation, but the effect on cancer development in our primary endpoint analysis is clear. Although the hazard ratio based on the intention-to-treat analysis was not significant, the more informative incident rate ratio, which takes account of multiple primary events in this genetically susceptible population, was significant with a p value of 0-05.