After a treatment has been approved and is being marketed, it is studied in a phase IV trial to evaluate side effects that were not apparent in the phase III trial. Thousands of people are involved in a phase IV trial.
PHASE IV TRIAL
Meaning of PHASE IV TRIAL in English
NCI English Dictionary of Cancer Terms. Английский словарь раковых терминов NCI(Национальный институт злокачественных новообразований). 2012