What does a clinical trial involve?

Volunteers for clinical trials can involve healthy people or patients. Clinical trials are done for many reasons. For example they may look at new treatments to see if they are more effective than the standard treatments already available. Or compare different ways of diagnosing an illness. There are also trials that look at prevention, screening and quality of life.

In cancer care treatment trials are the most common type of trial. They may be carried out to:

  • test new treatments, such as chemotherapy drugs and targeted therapies
  • look at new combinations of existing treatments, or change the way they are given, to make them more effective or to reduce 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.

Clinical trials provide the evidence that is needed for doctors and patients so they know which treatments are the safest and most effective.

This information is for people with cancer, who may have the option of joining a clinical trial as part of their cancer treatment. We refer to these people as patients.

Treatment trials

Treatment trials are the most common type of trial. In cancer care, they may be done to:

  • test new treatments such as new chemotherapy drugs and targeted therapies
  • look at new combinations of existing treatments, or change the way they are given, in order to make them more effective or to reduce side effects
  • compare the effectiveness of drugs used for symptom control
  • discover which treatments have fewer side effects
  • find out more about how cancer treatments work
  • see which treatments have the least impact on peoples’ everyday lives
  • see which treatments are the most cost-effective.

Treatment trials are the only reliable way of finding out whether a different operation, type of chemotherapy, targeted therapy or radiotherapy is better than what is already available.

If doctors already knew that a new treatment was better than the standard treatment, there would be no need for a clinical trial. Patients would be offered the treatment routinely as part of their care.

The treatment being tested may aim to:

  • improve survival (how long people live after treatment)
  • relieve the symptoms of cancer
  • reduce the side effects of treatment
  • improve quality of life or sense of well-being for people with cancer.

Many drugs that are now commonly used in cancer care have been previously tested in clinical trials. Without ongoing research, it wouldn’t be possible to add to our knowledge about effective treatments.


Prevention trials

Prevention trials look at whether a specific treatment may help to prevent a specific type of cancer. For example, trials have looked at whether people with a higher risk of cancer, because of their family history, would benefit from taking medicine to reduce their risk.


Screening trials

Screening trials look at new ways of testing a person for a specific cancer. These trials are often aimed at finding cancer early when the chance of a cure may be highest. They may be carried out in the general population. Or in people who are at a higher risk of cancer because of their family history.


Diagnostic trials

Diagnostic trials look at new ways of accurately finding a cancer – perhaps using new scans or tests. These trials usually include people who may have symptoms of cancer.


Quality of life trials

Quality of life trials look at ways of improving a person’s sense of well-being. Many quality of life trials are combined with treatment trials. This is because doctors want to know what effect a particular treatment has on a person’s everyday life. They often include questionnaires, which people complete at different stages during the trial. These may look at the psychological and financial impact of the treatment on both patients and their carers. For example, a trial might look at whether someone has to take time off work to care for you while you have treatment.

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