• A clinical trial is a research study used to assess the benefits and risks of a new treatment.

• There are various methods of comparing treatments within trials. Some allocate treatment at random; some allow participants to know which treatment they are taking whilst others do not; and some allocate some participants to receive a dummy drug rather than the trial drug.

• All trials lay down criteria for who can and cannot join the trial.

• All participants must give their fully informed consent to take part in the trial. Asking questions of your doctor and researchers involved in running the trial is part of the process of giving informed consent, and we suggest some relevant questions in this booklet.

• You should not feel pressurised into joining a trial. Similarly, don’t join a trial if you feel unsure you want to take part. However, you are free to leave a trial at any time, if you choose.

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