Clinical trials are medical research trials involving patients. They are carried out to try and find new and better treatments. Patients take part in trials in all areas of medicine, not just in cancer and not just to test treatment. For example, a clinical trial might be used to compare different ways of diagnosing an illness, or it might test techniques for preventing a particular cancer. Some trials also include a study of the psychological effects and financial impact of the treatment, on both patients and their carers. An example of this is whether someone has to take time off work to look after you.

Carrying out clinical trials is the only sure way to find out if a new approach to cancer care is better than the standard treatments currently used. Without trials, there is a risk that patients could be given treatments which have no advantage, waste resources and might even be harmful to them.

At the present time about 1 in 9 cancer patients take part in clinical trials. Trials are more commonly used with some cancers than with others.