Research has indicated that non-steroidal anti-inflammatory drugs (NSAIDs), including aspirin, have a protective effect against the development of colorectal cancer in patients with previous neoplasia. But the relative efficacy of different pharmaceutical agents is unknown.
To seek clarity, researchers performed a network meta-analysis of data from 14 clinical trials involving 12,234 patients who had previously been treated for colorectal polyps or cancer.
Reporting in The BMJ
, they found that, compared with placebo, non-aspirin NSAIDs were superior for preventing advanced metachronous neoplasia over follow-up of three to five years. Low-dose aspirin was ranked second for efficacy, but had the most favourable risk-benefit profile.
As non-aspirin NSAIDs carry a high risk of serious adverse events, the authors suggest that low-dose aspirin might therefore be preferable for all patients except those with previous high-risk neoplasia.
 Dulai PS, Singh S, Marquez E et al. Chemoprevention of colorectal cancer in individuals with previous colorectal neoplasia: systematic review and network meta-analysis. BMJ 2016;355:i6188; doi: 10.1136/bmj.i6188