What are randomised clinical trials?
Almost all phase 3 trials and some phase 2 trials are randomised. This means that the people taking part in the trial are put into different treatment groups at random. Randomised trials have two or more different treatment groups. There is usually a control group which has the standard treatment. The other group receive the new treatment or procedure that is being tested.
Randomised trials help the scientists to ensure that the results from the trial are reliable and not biased. For example, researchers may put healthier participants into a particular group without realising. These participants are likely to have better outcomes than those who are more unwell so it may make it seem like a particular treatment works better than it does.
What is the placebo effect?
Many people will feel better if they receive a fake treatment, known as a placebo, simply because they believe it will have a positive effect. This is known as the placebo effect. In order to make sure a treatment is actually working, the control group may be given a placebo. Participants would only be given a placebo if it is either given alongside standard treatment or if there is no standard treatment available. If there is no standard treatment, those given the placebo would not receive treatment if they were not taking part in the trial, so the trial does not put them at a disadvantage. It would be unethical to withhold cancer treatment from people who need it so regardless of whether you receive the new treatment, you will always be given the best available treatment and care.
To reduce the placebo effect, trials may be blinded or double-blinded. In blind trials, you do not know whether you have been given the new treatment or not. In double blind trials, neither you nor the doctor administering the treatment knows whether you have been given the new treatment.