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Frequently asked questions
- What are the phases of a clinical trial?
- What is a clinical trial protocol?
- Where are trials conducted?
- Who can participate in a trial?
- How are trial participants protected?
What are the phases of a clinical trial?
Most clinical research progresses in an orderly series of steps or phases.
- Phase I trials – the first studies to evaluate how a new drug should be administered (i.e., orally, intravenously, by injection), how often and in what dosage.
- Phase II trials – provide preliminary information about how well the new drug works, and generate more information about the drug’s safety and benefits. A Phase II study usually focuses on a particular type of cancer.
- Phase III trials – compare a promising new drug, combination of drugs or procedure with a current standard of treatment.
- Phase IV trials – include the continuing evaluation that takes place after Food and Drug Administration approval, when the drug is already on the market and available for general use (post-marketing surveillance).
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 it will study and how.
- Who may participate – criteria for participants who enter the study.
- What medications and medical tests will be used with the participants.
- What information is being searched.
Several research centers may be involved in the study, and each uses the same protocols to ensure that information from all centers can be combined and compared.
Where are trials conducted?
Large cancer centers, university hospitals, local medical centers or physician offices may be included in managing clinical trials. There may be only one or two locations involved in a particular study, or hundreds around the country.
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 health.
Eligibility criteria help assure that the study results answer the research question and identify who will benefit in the future from the approach being studied.
How are trial participants protected?
There are several procedures in place as part of the protocols to protect the safety of the people who participate. Two groups that oversee the safety procedures are the:
- Organization that sponsors the study (for example, the National Cancer Institute).
- The Institutional Review Board that oversees clinical research in the health care institution. The IRB includes physicians, other health care 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 ensure that the study is conducted fairly and that participants are not likely to be harmed.
Phase III trials also have a special group called a Data Safety and Monitoring Committee that looks at the test results, monitors the safety of the participants and decides whether the study should go forward as originally planned.
