A daily dose of aspirin should be given to people at high risk of bowel cancer, say scientists.
Two pills a day for two years reduced the incidence of bowel cancer by 63% in a group of 861 at-risk patients, a study reported in The Lancet said.
Newcastle University's Prof Sir John Burn, who led the study, said the evidence "seems overwhelmingly strong".
Other experts said the findings added to a growing body of proof that aspirin could be used in the fight on cancer, BBC reported.
The study was conducted on 861 patients with Lynch syndrome, which affects one in every 1,000 people.
They struggle to detect and repair damaged DNA which means they are more likely to develop a range of cancers including those of the bowel, womb and stomach.