Treatment-related clinical trials are usually carried out in a series of steps or phases.
Potential new cancer drugs or treatments are first tested in the laboratory (pre-clinical trials) before they’re given to people in trials. If it seems they may help to treat a particular cancer, they are tested in what are called phase 1 trials. If these are successful, the drug is used in phase 2 trials and then phase 3 trials. Phase 4 trials test drugs that are already licensed.
Feasibility studies and pilot studies may be carried out before a planned clinical trial. A feasibility study is designed to see how possible a clinical trial is. For example, it will look at how easy it will be to recruit people to the trial, how many people the trial might need and how long the trial could take to complete.
Pilot studies are a smaller ‘test’ version of the main clinical trial. They are done before the main study to check whether the ideas behind the trial and the suggested methods (the ‘trial design’) work in practice.
Researchers who run trials involving patients have to offer a treatment they believe is at least as good as, or possibly better than, the best treatment that is currently available. The trials have to be carried out following strict rules and guidelines.