Clinical trials research new treatments to see whether they are more effective than the standard treatments already available. This can be to test a new drug, research into different ways of performing an operation, or to find a new way of giving treatment. Their aim is to find new treatments that work better and have fewer side effects.

They can be carried out to:

• test new treatments, such as chemotherapy drugs, gene therapy, or cancer vaccines
• search for new combinations of existing treatments or change the way treatments are given so that they can be more effective or reduce the side effects
• compare the effectiveness of drugs used to control symptoms
• find out how cancer treatments work
• see which treatments are the most cost-effective.

There are also trials that focus on improving prevention, detection, diagnosis, and quality of life.