Taking aspirin each day decreases the risk of developing colorectal cancer but also increases the risk of gastrointestinal and cerebral haemorrhage. How can GPs balance those risks to determine who should take aspirin to prevent colorectal cancer?
An Australian study investigating factors associated with colorectal cancer was the first to suggest that aspirin may be protective.1 Subsequently, five large randomised population studies investigating the role of aspirin in preventing cardiovascular disease were analysed. They suggested that daily doses of at least 75mg of aspirin over five years reduced the risk of colon cancer by 24%, and mortality due to colon cancer by 35% over the long term.2 There was not the same impact on rectal cancer, and it appeared that the reduced incidence was largely in proximal colon cancer. Benefit increased with longer treatment duration.