There are three phases of clinical trials in which a treatment is studied before the treatment is eligible for approval by the FDA (Food and Drug Administration).
The purpose of a Phase I study is to find the best way to administer a
new treatment and to determine how much of it can be given safely.
Physicians watch patients carefully for any harmful side effects. The
research treatment has been well tested in laboratory and animal
studies, but the side effects in human patients are not completely
predictable in this phase.
Phase II trials determine the effectiveness of a research treatment
after safety has been evaluated in a Phase I trial. Patients are closely
observed for an anticancer effect by careful measurement of cancer
sites present at the beginning of the trial. In addition to monitoring
patients for response, any side effects are carefully recorded and
assessed.
Phase III trials require the entry of large numbers of patients; some
trials enroll thousands of patients. One of the groups may receive
standard (the most accepted) treatment so the new treatments can be
directly compared. The group that receives the standard treatment is
called the “control group.” For example, one group of patients (the
control group) may receive the standard chemotherapy for a certain type of cancer, like mesothelioma,
while another patient group may receive another type of chemotherapy
that may or may not contain an investigational drug to see if this
improves survival. All patients in Phase III trials are monitored
closely for side effects, and treatment is discontinued if the side
effects are too severe.
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