Could recommendations about aspirin prophylaxis enhance colorectal cancer screening programmes?

Abstract

A paper published in the March 2004 edition of the European Journal of Public Health evaluated the evidence on aspirin and colorectal cancer using the nine causality criteria originally put forward by Sir Austin Bradford-Hill in 1965.1 Using this framework, the evidence that aspirin might reduce the risk of colorectal cancer by 20–30% was evaluated as ‘suggestive’. Colorectal adenomas are putative precursors of sporadic colorectal cancer. A meta-analysis of four randomized controlled trials has provided evidence that aspirin, perhaps even in low doses, reduces the risk of colorectal adenoma recurrence by ∼30%.2 This meta-analysis provides further suggestive evidence that aspirin might exert chemopreventive benefits against colorectal carcinogenesis and thus reduce the risk of cancer developing. Adenomas, however, only offer a proxy measure of cancer risk and there are uncertainties and questions remaining about the evidence on aspirin and colorectal cancer chemoprevention.3 This includes the optimum dose, duration and frequency of aspirin that might achieve chemoprevention.3 These are important questions since aspirin increases the risk of undesirable effects, such as major bleeding. The consequences of these undesirable effects can be serious, even fatal in rare cases. …