Does aspirin really reduce the risk of colon cancer?

摘要

I was surprised to read the conclusions of the CAPP2 Investigators (Dec 17, p 2081)1 and the accompanying Comment.2 The study is neutral on its primary outcome and therefore any conclusions drawn should be guarded. Moreover, the previously published primary analysis3 had appropriately been interpreted as showing no benefit with aspirin. Repeated analyses increase the chances of a false-positive result. The distribution of events also seems distinctly odd, with an apparent gross excess of tumours only in the 11th and final year, by contrast with possible benefit confined to the first 18 months in the first report. A further few years' follow-up are required to determine whether these late effects arejustthe play of chance.