What does the search term ‘phase' mean?

‘Phase' is a term researchers use to differentiate different types of research. You can search for clinical trials based on the type of research being conducted. Research studies are each developed with very specific objectives and to obtain certain information to help find answers to research questions. Below is a summary of the different categories of research.

Pilot – Pilot studies are exploratory research trials. These studies are designed to investigate hypotheses, but not to find a definitive answer. These are usually smaller studies that generally try to find out if a problem exists and what directions researchers may want to take to find solutions. These may also be hypothesis-generating studies. The results of pilot studies will go on to larger studies that are designed to find a definitive answer.

Phase I-- Phase I trials are the first step in testing a new treatment in humans. These studies test the best way to give a new treatment (for example, by mouth, intravenous infusion, or injection) and the best dose. The dose is usually increased a little at a time in order to find the highest dose that does not cause harmful side effects. Because little is known about the possible risks and benefits of the treatments being tested, phase I trials usually include only a small number of patients who have not been helped by other treatments.

Phase I/II or IB-- A trial to study the safety, dosage levels, and response to a new treatment.

Phase II-- Phase II cancer trials test whether a new treatment has an anticancer effect (for example, whether it shrinks a tumor or improves blood test results) and whether it works against a certain type of cancer.

phase II/III or IIB-- A trial to study response to a new treatment and the effectiveness of the treatment compared with the standard treatment regimen.

Phase IV-- 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.