About Clinical Trials: Information from the National Cancer Institute
What are clinical trials?
Clinical trials are studies, managed by government agencies, educational institutions,
private not-for-profit organizations, or commercial businesses. They develop and evaluate
the effectiveness of new treatments for diseases.
What are some types of clinical trials?
According to the National Cancer Institute, there are different types of cancer clinical
Prevention trials. These are designed to test therapies that might keep cancer from developing in people
who have not previously had cancer. Some cancer prevention trials are designed to
test treatments that might prevent a new type of cancer from developing or keep cancer
from coming back in people who have already had cancer.
Early detection or screening trials. These are done to evaluate ways to find cancer, especially in its early stages.
Treatment trials. Such trials test new therapies in people who have cancer.
Quality of life studies. These are done to improve comfort and quality of life for people who have cancer.
Behavioral studies. Such studies are done to evaluate ways of changing behaviors that cause cancer, such
as tobacco use.
Genetic studies. These studies address how your genes affect finding, diagnosing, and treating cancer.
What are the phases of a clinical trial?
Most clinical research progresses in an orderly series of steps or phases:
Phase 0 trials. These are the earliest steps in testing new treatments in humans. A small number
of people are studied and the focus is on learning how the agent is processed by the
body and how the agent affects the body. No information is gathered on safety or effectiveness
in treating cancer.
Phase I trials. These are the first studies to evaluate how a new therapy should be given, how often,
and in what dosage. The focus is to determine safety (drug dose, device safety, or
other therapy's safety) for the next phase of testing.
Phase II trials. These provide preliminary information about how well the new therapy works. They
also generate more information about its safety and benefits. A Phase II study usually
focuses on a particular type of cancer.
Phase III trials. These compare a promising new therapy, combination of treatments, or procedure with
a current standard of treatment. These trials often enroll large numbers of people.
They may be done at healthcare providers' offices, clinics, and cancer centers nationwide,
or even worldwide.
Phase IV trials. These include the continuing evaluation that takes place after FDA approval, when
the therapy is already available for general use.
What is a clinical trial protocol?
Clinical trial protocols are the action plans or guidelines that must be followed
during the course of any study. Guidelines may cover:
The design of the study — what will be studied and how
Who may participate — criteria for patients who enter the study
What treatments and medical tests will be used to follow the participants
Specific research questions
What information will be collected
Several research centers may be involved in the study. Each uses the same protocols
to make sure that information from all centers can be combined and compared.
Where are trials conducted?
Large cancer centers, university hospitals, local medical centers, or healthcare provider
offices may be included in managing clinical trials. Informed consent is a process
designed to protect potential participants through detailed description of important
facts about a specific clinical trial. There may be only one or two locations involved
in a particular study, or hundreds around the country, or even around the world.
Who can participate in a trial?
Each protocol in a trial defines specific characteristics, called eligibility criteria,
that participants should have in order to participate in the study. Characteristics
may include type of disease and its stage, as well as the participant's age and general
Eligibility criteria help researchers know for sure that the study results answer
the research question and identify who will benefit in the future from the approach
How are trial participants protected?
There are several procedures in place, as part of the protocols, to protect the safety
of the participants. Informed consent is a process designed to protect potential participants
through detailed description of important facts about a specific clinical trial. Two
groups that oversee the safety procedures are the:
Organization that sponsors the study, for example, the National Cancer Institute
Institutional Review Board (IRB) that oversees clinical research in the healthcare
institution. The IRB includes healthcare providers, consumers, and sometimes members
of the clergy, who do not have any personal interest in the results of the study.
As neutral reviewers, they make sure that the study is conducted fairly and that there
is not a high probability of harm to the participants.
Some clinical trials, especially Phase III trials, also have a special group called
a Data Safety and Monitoring Committee. This group looks at the test results, monitors
the safety of the participants, and decides whether the study should go forward as
For information on how to participate in a clinical trial, please talk with your healthcare