About Add-Aspirin

The Add-Aspirin trial is for people who have had, or have started treatment for, cancer of the breast, stomach, oesophagus (food pipe), prostate or bowel (see Who can take part?)

We are aiming to find out whether taking aspirin daily for 5 years after treatment for an early stage cancer (cancer that has not spread widely) stops or delays the cancer coming back. This study will compare groups of people who take aspirin and those who take placebo tablets (see What is a placebo?).

This trial is randomised (see What are randomised controlled trials?). This means that people taking part are put into the treatment groups at random by a computer. Neither the participant nor their doctor will know or be able to decide whether the participant is taking aspirin or a placebo.

For more information on the trial treatment please click here, and see the Participant Information Video below.

This video is approved for UK use only.

Add-Aspirin Participant Information Video

This video has received ethical approval in the UK.


  • Recruitment into the breast cohort has now ended.
  • The doses of aspirin being evaluated in the trial are 100mg, 300mg or placebo.
  • With the ongoing COVID-19 pandemic, if existing participants have concerns about attending follow-up visits in person, they should contact their study doctor or nurse.
  • Until the final results of the study are available, we would not recommend aspirin is taken over the counter outside of the trial (unless prescribed by your doctor for a clinically indicated reason), as we do not currently have definitive evidence to demonstrate the effect of aspirin in preventing cancer recurrence.

Contact Details

If you are an individual who is interested in taking part in Add-Aspirin, please talk to your doctor who will be able to consider whether you are suitable for the trial.

For healthcare professionals

Please log into the members area for Add-Aspirin contact details.

Register Interest

For healthcare professionals

If your centre would like to recruit participants to Add-Aspirin, contact us:

Register a participant

From Monday 16th March 2020, to RANDOMISE a participant in the UK please call +44 (0)20 7670 4925, rather than the usual randomisation line.

To RANDOMISE a participant from Republic of Ireland or India only, please use the 'Register a participant' link above to randomise online. Please make sure to press 'Randomise' once logged in to the server.

We have been experiencing intermittent issues with the trial websites. In the event of an emergency unblinding outside of office hours (including over the Easter bank holidays), if the usual unblinding links are not working, please telephone +(0)20 7670 4906 or +(0)20 7670 4892 to reach one of the Trial Managers.

Unblind a participant in the UK

Unblind a participant in the RoI

Unblind a participant in India