What Are Clinical Trials?
Clinical trials are research studies designed to find new and better ways to
treat patients with cancer and other diseases.
Physicians and scientists conduct clinical trials to find out:
- whether a newly developed treatment is safe and effective for cancer patients
- how and in what dose the new treatment is best administered
- whether the treatment is better than other treatments
Clinical trials may test new drugs, new approaches to using existing treatments,
or newly developed methods of treatment.
Clinical trials are unique studies in that they rely on the participation of
patients to test the new therapies. They are conducted only after a long process
of research on the new treatment has already been completed.
Before ever testing a new treatment with people, studies are performed in research
labs and with animals to examine possible benefits and side effects. By the
time the treatment is given to patients in a clinical trial, it has been under
study for many months or years.
When planning a clinical trial, an investigator (usually a physician) must
write a detailed plan that outlines both the background and purposes of the
study and the exact way in which the study will be conducted. This plan or "protocol"
details each step of treatment and care for patients in the study, and it must
be approved by scientific review boards within the investigator's institution
and within the organization that sponsors the study. The protocol for the study
ensures that the patients in study receive appropriate treatment and high-quality
care and that the research is conducted scientifically.
Clinical trials are conducted in three phases, each aimed at answering a different
research question. Each newly developed treatment must go through all three
- Phase I trials: These first studies in people evaluate how a new
drug should be given (for example, by mouth, injected into the blood, or injected
into the muscle), how often, and in what dose. Phase I trials are the first
tests of a new treatment in humans, so they usually include 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. Like Phase I trials, they often
include a limited number of patients.
- 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
for treatment. Participants are usually assigned at random either to the standard
treatment group or to the new treatment group (this process is called randomization).
Phase III trials often enroll large numbers of people and may be conducted
at many doctors' offices, clinics, and cancer centers nationwide.
Find a Clinical Trial
To find a clinical trial, search our clinical trials database by topic (keyword), study number, or investigator.
This page was last updated: April 13, 2015