Long-term use of low-dose aspirin and non-aspirin NSAIDs seems to reduce the risk of developing colorectal cancer (CRC), new research suggests.

A Danish study included 10,280 patients with their first diagnosis of CRC and 102,800 controls. Ever use (≥ 2 prescriptions) of low-dose (75-150mg) aspirin did not statistically influence CRC risk. Ever use of non-aspirin NSAIDs reduced CRC risk by 6 per cent. However, taking low-dose aspirin continuously for at least five years was associated with a 27 per cent reduction in CRC risk.

Taking at least 0.3 average defined daily doses of non-aspirin NSAIDs for at least five years was associated with a 30 per cent reduction in CRC risk. Consistent use for at least five years (≥ 2 prescriptions annually) was associated with a 36 per cent reduction. The reduction in CRC risk was greater with long-term use of more COX-2 selective drugs (43 per cent) than nonselective NSAIDs (27 per cent).

The authors could not allow for use of OTC aspirin and ibuprofen, NSAID dosing schedules and some potential confounders. They add that side-effects, such as gastrointestinal bleeding and cardiovascular risks, will need to be balanced against the benefits on CRC risk. (Ann Intern Med doi:10.7326/M15-0039)