Aspirin in the prevention of cancer

Abstract

Peter Rothwell and colleagues, in their meta-analysis of randomised trials (Jan 1, p 31), show that low-dose long-term aspirin use reduces the risk of several cancers. Before this information was available, the balance of benefi t and harm in taking aspirin in the primary prevention of coronary heart disease and stroke (cardiovascular disease [CVD]) was uncertain. The new data on cancer help to clarify the net benefi t of aspirin, particularly if aspirin were included with a statin and bloodpressure-lowering drugs in a combined formulation (Polypill). The table shows the estimated number of fi rst CVD events and cancer deaths prevented in England and Wales in 1 year on the basis of a Polypill (composed of three blood-pressurelowering drugs at half standard dose and a statin at standard dose such as simvastatin 40 mg), with or without aspirin. In people aged 55–89 years, for example, 186 000 CVD events and cancer deaths would be prevented. The table shows that 120 such outcomes would be prevented in 1000 people over a period of 20 years (or 170 per 1000 over 35 years). Aspirin causes substantially fewer major extracranial bleeds that require a blood transfusion than the number of CVD events and cancer deaths prevented (table). However, the risk of an aspirin-induced major extracranial bleed increases with age. The estimates for such bleeds shown in the table among people aged 55 years over a period of 20 years are based on observed data and are likely to be accurate, but the numbers in people older than 75 years are uncertain— they would be twice those shown if the age trend to 75 years continues to 90 years. Given the results published by Rothwell and colleagues, the balance of the evidence is in favour of including aspirin in a Polypill strategy to prevent CVD and cancer. NW and ML hold a European and Canadian patent (pend ing in the USA) for the Polypill, fi led in April 2000.