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Why are we running this study?

Aspirin is a common drug that is used as a painkiller and to prevent further heart attacks and strokes in some people. Some studies have suggested that people who regularly take aspirin may be less likely to be diagnosed with cancer than those who don’t take aspirin. In studies testing the beneficial effect of aspirin on heart disease, aspirin appeared to reduce the number of people who developed cancer, and if people did develop cancer, it appeared to be less likely to spread. So researchers believe that aspirin may stop cancer coming back in people who have had treatment for early stage cancer. But, importantly, there is not any reliable evidence yet since previous studies were not specifically designed to answer this question.

A clinical trial or study is the best way to test this. It will look at both the benefits and the side-effects of taking aspirin in a large group of people who have had cancer. The study will look at two different doses of aspirin. This is because little is known about how much aspirin may be needed to have an effect, if any, against cancer.

What is the usual treatment?

Usually, people like you, who have had or have started treatment for early stage cancer, will visit hospital for regular check-ups once the treatment has finished. People who have had prostate cancer sometimes also take long-term hormone treatment. People who have had breast cancer sometimes also take long-term hormone treatment or Trastuzumab (Herceptin). This will continue if you take part in the study. People who have had stomach, oesophagus or bowel cancer don’t usually take any other long-term treatments.

What are randomised control trials?

Randomised controlled trials (RCTs) are a type of clinical trial. RCTs aim to make a fair comparison between a new treatment and the existing treatment, or between two (or more) existing treatments, to see which works best.

A controlled trial compares two or more groups of people: one or more experimental group(s) who receive a new treatment, and a control group, who receive the current standard treatment (which might be the best existing treatment, no treatment or a placebo. Information from the follow-up of the control group allows the researchers to see whether the new treatment(s) they are testing are more or less effective than the existing treatment.

The decision about which treatment each participant in a randomised controlled trial receives is made at random – based on chance, rather than decided by the doctor or participant. This process is called randomisation. To make sure the results are as reliable as possible, neither the participants, nor the doctors, will know or be able to choose who is taking aspirin and who is taking a placebo.

Randomisation ensures that the two (or more) groups of people in a trial are as similar as possible, except for the treatment they receive. This is important because it means that researchers can be sure that any differences in outcomes between the groups are only due to the treatment received.

Randomisation is the best way of ensuring that the way the participants in each group are selected does not bias, or affect, the results of the trial. For example, if a doctor chose which treatment a patient should receive as part of a trial, she or he might give the new treatment to sicker patients, or to younger patients. This would make the results of a trial unreliable, as it could exaggerate or hide the effects of the treatment.

Randomised controlled trials are the most reliable way to compare treatments. View the Treatment in the Add-Aspirin trial webpage for more information.

What is a placebo?

A placebo is a “dummy” tablet. It looks like an aspirin tablet but it doesn’t contain any medicine.
We are using a placebo in this study so that we can make as clear an assessment as possible about the effects of aspirin.

Who can take part?

Individuals will only be able to take part in the study if the hospital where they are being treated is participating in the trial. 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.

Individuals can take part in the Add-Aspirin study if they have had (or are currently having) treatment for an early stage cancer of the breast, bowel, stomach, oesophagus or prostate. In the UK and Republic of Ireland, recruitment into the breast and bowel cancer groups has ended but continues in the stomach, oesophagus and prostate groups. Individuals who have taken part in other trials and satisfy the eligibility criteria might also be eligible:

Individuals cannot take part in the study if they regularly take aspirin, non-steroidal anti-inflammatory drugs (NSAIDs, e.g. ibuprofen), anti-coagulants (e.g. warfarin) or are at risk of developing side effects from aspirin (e.g. a stomach ulcer). Visit the eligibility webpage for a full list of eligibility criteria.