(Date reviewed: 12/23/2003) - Clinical trials are research studies in which
people help doctors find ways to improve health and cancer care. Each study
tries to answer scientific questions and to find better ways to prevent,
diagnose, or treat cancer.
A clinical trial is one of the final stages of a long and careful cancer
research process. Studies are done with cancer patients to find out whether
promising approaches to cancer prevention, diagnosis, and treatment are safe
and effective.
Most clinical research that involves the testing of a new drug progresses in an
orderly series of steps, called phases. This allows researchers to ask and
answer questions in a way that results in reliable information about the drug
and protects the patients. Clinical trials are usually classified into one of
three phases:
-
Phase I trials: These first studies in people evaluate how a new drug
should be given (by mouth, injected into the blood, or injected into the
muscle), how often, and what dose is safe. A phase I trial usually enrolls only
a small number of patients, sometimes as few as a dozen.
-
Phase II trials: A phase II trial continues to test the safety of the
drug, and begins to evaluate how well the new drug works. Phase II studies
usually focus on a particular type of cancer.
-
Phase III trials: These studies test a new drug, a new combination of
drugs, or a new surgical procedure in comparison to the current standard. A
participant will usually be assigned to the standard group or the new group at
random (called
randomization). Phase III trials often enroll large numbers of people
and may be conducted at many doctors' offices, clinics, and cancer centers
nationwide.
Back to Top |