Background Observational studies report reduced colo rectal cancer in regular aspirin consumers. Randomised
controlled trials have shown reduced risk of adenomas but none have employed prevention of colorectal cancer as a
primary endpoint. The CAPP2 trial aimed to investigate the antineoplastic eff ects of aspirin and a resistant starch in
carriers of Lynch syndrome, the major form of hereditary colorectal cancer; we now report long-term follow-up of
participants randomly assigned to aspirin or placebo.