Why Are Randomization and Placebos Included in Many Cancer Trials? | Oncology | JAMA Oncology | JAMA Network
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JAMA Oncology Patient Page
May 20, 2021

Why Are Randomization and Placebos Included in Many Cancer Trials?

Author Affiliations
  • 1City of Hope Cancer Center, Pasadena, California
  • 2Division of Cancer Treatment and Diagnosis, National Cancer Institute, Bethesda, Maryland
JAMA Oncol. Published online May 20, 2021. doi:10.1001/jamaoncol.2021.0896

People often find it challenging to understand certain aspects of clinical trial research and design. One of these is randomization, when trial participants are randomly assigned to 1 treatment among 2 or more options. A second is that the study may include a placebo, an inactive version of a medication that is given to mimic the process of receiving active medication. Why are they a part of clinical trials?

Patients are randomized to different treatments to ensure that trial participants receiving different therapies are as similar as possible. In a trial without randomization, patients may be assigned to one treatment or another based on patient or physician choice. This leads to bias, an unintended preference for one approach over another. When bias is present, findings between groups can be due to differences in patient characteristics rather than treatment-related effects. Here are some examples of unintended biases:

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