Clinical Trials Glossary | Sarcoma UK
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Clinical Trials Glossary

Blind trial

The patient is not told whether they are part of the trial group or the control group.

Controlled trial

Patients who are participating in the trial are split into two groups; those who receive the new drug or treatment (trial group) and those who receive the standard treatment (control group). The control group may be given the standard treatment used currently, in some cases they are given no treatment or a placebo.

Double blind trial

Neither the clinicians nor the patient knows which groups the patients have been allocated to.

Eligibility Criteria

Each trial will have a list of eligibility criteria. This is a list of characteristics that all patients must have to be accepted onto the study. It is sometimes described as inclusion criteria (characteristics you must have to take part in the study) or exclusion criteria (characteristics that are not accepted to the study).

Types of eligibility criteria can include:

  • Age
  • Type of sarcoma
  • The stage of your disease
  • Medical history
  • Current health status

Phases of clinical trials

Clinical trials are defined in four phases; however, you are most likely to come across phases one to three.

Phase 1

These trials test the safety of a treatment or drug. They are done to find out:

  • The safe dose range
  • What the side effects are
  • How the body copes with the drug
  • If the treatment shrinks the cancer

Phase 2

These trials test how cancer responds to which treatment. They aim to:

  • See if the treatment works well enough to test in a phase 3 trial
  • Find out which type of cancer the treatment works for
  • Learn more about the side effects and how to manage them
  • Learn more about the best dose to use
  • Sometimes a phase 2 trial will compare a new treatment with another treatment already in use, or with a dummy drug called a placebo.

Phase 3

These trials compare new treatments with the best currently available treatment, often called the standard treatment. These trials may compare:

  • A new treatment with the standard treatment
  • Different doses or ways of giving a standard treatment
  • A new way of giving radiotherapy with the standard way

Phase 4

These trials test drugs which are already licensed. They tend to look at:

  • Long term effects of the drug
  • The use of the drug with different types of people or demographics


This is a non-active treatment. It will look the same as the new treatment drug given to the trial group. Trials using placebos alone are only used when there is no alternative treatment available. Often a placebo is used in addition to an existing treatment when the trial is looking at a combination of drugs.


A computer chooses which group (trial group or control group) patients are allocated to.

Standard treatment

Treatment that is normally given to people with a specific condition.


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