A treatment given in addition to the main form of treatment (e.g. chemotherapy in addition to surgery) that aims to delay or prevent recurring disease by destroying possible remaining cancer cells.


A section of a trial that receives the same treatment. A trial with a treatment and a control group would be called 2-armed.

Blinded Trial

A trial in which people don’t know whether they’re in the intervention group or the control group. This prevents people from reporting benefits because they believe they’re receiving a new treatment.

Control Group

The group of patients receiving the standard treatment or placebo in a clinical trial.

Controlled Trials

Trials designed to compare a new treatment against the standard existing treatment. One group (the trial or intervention group) are given the new treatment, while the other group (the control group) are given the standard existing treatment. If there is no existing treatment, the control group might be given a ‘placebo’.

Double-blind Trial

In these trials neither the patient nor the doctor knows which group the patient is in. This prevents doctor’s expectations from influencing their observations.


Endpoints describe the overall goals of the study. They often include things like overall survival, tumour response or quality of life.


The ‘line’ of treatment describes the order it’s used in. A first-line treatment is the initial treatment given. A second-line treatment is given when a first-line treatment doesn’t work.

Informed Consent

A form that a participant signs to indicate they that understand all the information they’ve been given about the trial, and agree to take part.

Open-label trial

A study where participants and doctors are aware of which treatment has been assigned. The opposite to a double-blind trial.


A drug designed to look like the drug being tested, but that does not have any effects. By comparing the effects of a treatment to the effects of a placebo, researchers can find out how effective the new treatment really is.

Principal Investigator

The scientist or doctor in charge of the clinical trial.


A plan that outlines how a clinical trial will be carried out, and why it is being done.

Randomised Trial

A trials in which patients are randomly allocated to groups to ensure the treatment and control groups have a similar mix of people of different ages, sexes and states of health.


An unintended effect of a drug or treatment.

Standard Treatment

The best proven treatment based on testing.

Treatment Group

The group of patients receiving the new treatment in a clinical trial.