Do cancer clinical trials use placebos?

Placebos are rarely used in cancer treatment trials. In most cancer trials, one group receives the new treatment being studied, while another group receives the treatment already considered the standard of care for that cancer. Researchers then compare how each group does.

Placebos are more likely to appear in a few specific situations: when there's no standard treatment available for the condition being studied, when researchers are comparing standard treatment plus a placebo against standard treatment plus the study drug, or in some cancer prevention trials.

If a trial does use a placebo, you are always told ahead of time, and this information is included in the informed consent process and the consent form you review before deciding whether to join. That means you can ask questions about placebo use before you agree to anything, including how likely you'd be to receive it and what you'd still receive if you did.