The anti-cancer effects of aspirin are controversial in academic circles. New findings from the University of Oxford provide strong evidence for the anti-cancer effects of aspirin. Daily aspirin use reduces the incidence of adenocarcinoma in the long term, while its effect on mortality is also evident after several years, suggesting that aspirin inhibits tumor growth and metastasis. The results of the study were published online in the March issue of The Lancet. The study consisted of five large randomized controlled trials in UK-based cardiovascular patients, with the trial group taking aspirin (≥75 mg) daily and recording the incidence of cancer in all patients. The anti-metastatic effect of aspirin was then observed, with cancer patients classified according to tissue and clinical characteristics, adenocarcinoma versus other. A total of 17,825 patients participated in the experiment, regardless of gender, and the greatest benefit was observed in smokers. Low-dose, slow-release aspirin preparations resisted platelet agglutination, but compromised bioavailability. Apparently, aspirin reduces mortality in cancer patients mainly because of its inhibitory effect on metastasis. The present study suggests that aspirin is useful in the treatment of certain cancers, particularly adenocarcinoma.