The FDA shared its latest thinking on the use of placebos in oncology trials in a final guidance highlighting ethical concerns about the use of “sham surgical procedures.”

Sponsors should only consider the use of placebos when surveillance is the standard of care, or with add-on trial designs such as repeated intravenous treatments via an indwelling catheter, the agency says.

The agency cautions against blinding in trials without explicit justification for exposing patients to risk, noting that placebos present an ethical concern as some patients are not receiving the effective therapy.