Clinical research studies are designed to help doctors discover new and improved ways of preventing, diagnosing, and treating cancer. This often means that doctors need to compare a new treatment or procedure with the current approach. To do this, studies may be designed to use placebos or randomization - two tools that allow researchers to understand how their new approach differs from the standard.
As a patient, placebos and randomization may mean that your course of treatment on a trial is no different from what you would recieve if you had not participated. You may wonder what the benefit is of participating in a trial if you only have access to the standard care. Your participation - even if you recieve a placebo - ensures that the research is scientifically rigorous. This helps both doctors and patients feel confident that new treatments that are discovered through clinical trials will be both safe and effective. Learn more about placebos and randomization below.
What is a Placebo?
A placebo is designed to look like the medicine being tested, but it is not active as a treatment. It helps researchers to understand how well their new treatment works in comparison with the standard treatment. Placebos may be used in a clinical trial that compares standard treatment plus a placebo, with standard treatment plus a new treatment. Placebos are rarely used alone in cancer clinical trials - typically only if there is no standard treatment.
You always will be told if a study uses a placebo. However, when you participate in a trial with a placebo, you and your care team may not know if you are recieving the placebo or the active treatment. This ensures that both the doctor and patient are not biased by their expectations about the effects of the treatment.
Why is Randomization Part of Clinical Trials?
In some phase 2 and all phase 3 clinical trials, patients are assigned to groups that receive different treatments. The process of assigning patients to these groups by chance is called randomization. In the simplest trial design, one group receives the new treatment. This is the investigational group. The other group receives standard therapy. This is the control group. At several points during and at the end of the clinical trial, researchers compare the groups to see which treatment is more effective or has fewer side effects. A computer is usually used to assign patients to groups.
Randomization, in which people are assigned to groups by chance alone, helps prevent bias. Bias occurs when a trial's results are affected by human choices or other factors not related to the treatment being tested. For example, if doctors could choose which patients to assign to which groups, some might assign healthier patients to the treatment group and sicker patients to the control group, without meaning to. This might affect trial results. Randomization helps ensure that this does not happen.
If you are thinking about joining a clinical trial that includes randomization, it is important to understand that neither you nor your doctor can choose which treatment you will receive.
Text adapted from the National Cancer Institute; images provided by Genentech. Reviewed on November 15, 2023.