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Research and new methods

The control group: the basis for comparison

To know whether a new treatment really helps, it has to be compared with something. A control group is created for this.

Last updated: ~1 min read
A heap of identical white tablets on a blue surface
Figure 1.In a blinded trial the medicines look the same

01Short answer

The control group usually receives current standard treatment. In cancer trials, when an effective treatment exists, no one is given a placebo alone; a placebo is used only on top of standard care or when there is no standard, and participants are told in advance. The control group makes it possible to check that a result is not due to chance, the natural course of the disease or expectations.

02Simple explanation

Comparison is needed.

Usually standard care.

Placebo alone: no.

Rules out chance.

03Scientific explanation

NCI: in cancer trials, a placebo is rarely used alone when an effective treatment exists; the control group receives standard treatment.

NCI: new treatments are tested step by step, from the laboratory to clinical trials; only those proven safe and beneficial become standard care.

04What happens in the body?

Placebo

A look-alike preparation with no active ingredient.

A steady light
Figure 2.A steady light — The control group: the basis for comparison

Placebo effect

The influence of expectations on how people feel.

Scales
Figure 3.Scales — The control group: the basis for comparison

How to read the news

Research news brings hope, but not every advance suits everyone. Look at who it was tested in, at what phase and in how many people.

Talk to your doctor

Show your doctor what you have read; they will explain how it relates to your diagnosis and treatment. Do not change your treatment on your own.

05From research news to a conversation: four steps

Read, check, ask, decide together.

Read — From a trusted source.1ReadFrom a trusted source.
Check — Phase, participants, result.2CheckPhase, participants, result.
Ask — Show your doctor.3AskShow your doctor.
Decide — Together, without rushing.4DecideTogether, without rushing.
SourceA trusted site.
DoctorA personal explanation.
SafetyNot changing treatment yourself.

06Key points at a glance

TopicIn brief
PlaceboA look-alike preparation with no active ingredient.
Placebo effectThe influence of expectations on how people feel.
How to read the newsResearch news brings hope, but not every advance suits everyone. Look at who it was tested in, at what phase and in how many people.
Talk to your doctorShow your doctor what you have read; they will explain how it relates to your diagnosis and treatment. Do not change your treatment on your own.

07Key terms

Control group
The group receiving standard care for comparison.
Placebo
An inactive preparation.
Clinical trial
Testing a new treatment with volunteers.
Evidence
A result confirmed by reliable research.

08Key points

  • Compare.
  • Be fair.
  • Be open.
  • Check the source.
  • Talk to your doctor.

09Frequently asked questions

Could I be given only a placebo?

In leukaemia, if effective treatment exists, usually not; the consent form says so.

Is it bad to be in the control group?

No; you receive the best known treatment.

Is this advance right for me?

Only your treating doctor can say, based on your diagnosis, stage and condition.

10Questions for your doctor

Take these questions to your appointment. The ones you save are collected on the “My questions” page and stay on this device only.

  1. Could I be given only a placebo?

  2. Is it bad to be in the control group?

  3. Is this advance right for me?

My questions

12Sources

  1. National Cancer Institute. Placebos in Cancer Clinical Trials
  2. National Cancer Institute. NCI Dictionary of Cancer Terms: control group
  3. National Cancer Institute. What Are Clinical Trials?
  4. National Cancer Institute. Phases of Clinical Trials
  5. National Cancer Institute. Using Trusted Resources
  6. World Health Organization. International Clinical Trials Registry Platform
  7. National Cancer Institute. Patient Safety in Clinical Trials
  8. National Cancer Institute. NCI Dictionary of Cancer Terms: informed consent
  9. NIHR. Be Part of Research
  10. NHS. Clinical trials
Medical disclaimerThis information is for educational purposes only and does not replace medical advice.
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