What are clinical trials?

Clinical trials are medical research studies involving people. All new treatments have to be thoroughly tested. Researchers test possible new drugs in the laboratory to begin with. If they look promising, they are carefully tested in people.
Clinical trials look at
  • Risks and causes – how genetics, lifestyle and other factors can increase people's risk of cancer
  • Preventing cancer – using drugs or lifestyle changes to reduce risk
  • Screening – tests for people with higher than average risk of cancer or for the general population
  • Diagnosing cancer – new tests,  scans or procedures 
  • Treatments – new drugs or combinations of drugs. Trials also look at new doses of drugs or new ways of giving treatment and new types of treatment
  • Controlling symptoms or side effects – new drugs or complementary therapies
  • Support and information - for people with cancer and their carers, families or friends
The 5 minute video below tells you more about clinical trials:

Cancer Research Trials | Cancer Research UK


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Read the full video transcript.

The aim of clinical trials

Trials aim to find out if a new treatment or procedure:

  • is safe
  • has side effects
  • works better than the currently used treatment
  • affects quality of life Open a glossary item

What trials tell us

Some trials will show that a new treatment works better than an existing treatment. Others will tell us more about the side effects, or what happens to the drug in the body.

Not all clinical trials will result in new and better treatment. Results sometimes show that:
  • the treatment being tested does not work or
  • that it has side effects that are worse than with existing treatments. 

This information is also useful for researchers and doctors, and in the end for patients. It all adds to our knowledge of cancer and how best to treat it.

Researchers also want to look at the impact a treatment has on you and your life. How often you have to travel to the hospital, for example. Studies that look at the effect a treatment or procedure has on your day to day life are sometimes called quality of life studies. Many trials include a quality of life study.


Oxford Handbook of Clinical and Healthcare Research (1st edition)
R Sumantra, S Fitzpatrick, R Golubic and others
Oxford University Press, 2016

Related information


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Please note - unless we state otherwise in the summary, you need to talk to your doctor about joining a trial.

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