The world’s largest ever clinical trial looking at whether taking aspirin daily can stop some forms of cancer returning has launched today, October 22, in the United Kingdom. The study is funded by the British National Institute for Health Research and the charity Cancer UK.
The study, called Add-Aspirin, will involve 11,000 patients who recently had, or are currently having, treatment for stomach, prostate, esophagus, breast or bowel cancer. Over 100 centers across Britain will be involved in the study, which should be published in November 2026.
The regular intake of aspirin has been proven to lower strokes and heart attacks in some people, and there are been indications that the drug can prevent some types of cancer.
The study will compare three groups of people, two taking different doses of aspirin (100 milligrams or 300 milligrams) and a third taking a placebo. The drug (or placebo) will be taken daily for five years, with follow-up observations in the subsequent years. The study is randomized, meaning the researchers don’t select who gets the drug and who gets the dummy tablet. It is also a double-blind trial, whereby neither the recommending doctors nor the patients know if they are taking the placebo or the aspirin. Randomized controlled trials such as this are the most reliable way to compare treatments.
Dr Ruth Langley, the chief investigator from the MRC Clinical Trials Unit at University College London, said in a statement: “There’s been some interesting research suggesting that aspirin could delay or stop early stage cancers coming back, but there’s been no randomized trial to give clear proof. This trial aims to answer this question once and for all. If we find that aspirin does stop these cancers returning, it could change future treatment – providing a cheap and simple way to help stop cancer coming back and helping more people survive.”
Low-dose aspirin is already prescribed daily to many patients, but due to the potential side-effects, researchers want to be certain that the results are worth the risk. This trial will hopefully provide an answer once and for all.
More information on the trial can be found on the Add-Aspirin trial page.