Watch the Cancer.Net Video: Clinical Trials and Safety with Eric Singer, MD, MA , adapted from this content.
- Clinical trials are regulated and monitored by independent committees and federal agencies to ensure the study is safe and scientifically relevant.
- Informed consent is the ongoing process designed to protect the rights and safety of a patient participating in a clinical trial.
- Patients are free to leave a clinical trial at any time for any reason.
Patient safety is the highest priority in clinical trials. Clinical trials are governed by a rigorous review and oversight process designed to protect the rights and safety of people who enroll.
Regulation of clinical trials
Various committees and agencies oversee patient safety in clinical trials.
Institutional Review Board (IRB). An IRB is an independent committee of doctors, statisticians, community advocates, and others who ensure that a clinical trial is ethical and that the rights of study participants are protected. Every clinical trial in the United States must be approved and monitored by an IRB to make sure the risks are as low as possible and that any risks are outweighed by the potential benefits. All institutions that conduct or support medical research involving people must, by federal regulation, have an IRB that approves the clinical trial before it begins and reviews the research periodically until it is completed.
Federal agencies. Federal agencies also approve and monitor clinical trials, including the U.S. Food and Drug Administration (FDA) and the National Institutes of Health (NIH). The FDA and the NIH are responsible for approving drugs and monitoring research. Both agencies make regulations to ensure the safety of clinical trial participants.
Data Safety Monitoring Board (DSMB). The DSMB is a group of doctors, medical ethicists, statisticians, and other health professionals that monitors the clinical trial for safety and scientific relevance during the trial. For example, if the new treatment is causing many patients to drop out of the study because of severe side effects, the DSMB may recommend stopping the study. Alternatively, sometimes the new treatment works so well that it is unethical to continue to give one group of patients the standard treatment. In this case, the DSMB may recommend stopping the standard treatment and offering those people the new treatment. A DSMB is especially useful for large clinical trials that are taking place in many cities because they review all of the data from each clinical trial location.
A DSMB is separate from an IRB. The IRB usually looks at the clinical trial before it starts. The DSMB reviews the study after it starts and makes recommendations to the IRB about stopping or continuing the study.
Research institutions are required to obtain informed consent from every clinical trial participant. It is important to understand that there is an informed consent document and an ongoing informed consent process. The informed consent document provides the patient with written information on all aspects of the clinical trial, and all patients need to sign the document before participating in the study. During the ongoing informed consent process, the research team should list all of the patient's options so that the person understands how the new treatment differs from the standard treatment. They must also list all of the risks of the new treatment, which may or may not be different from the risks of standard treatment. Finally, the research team must explain what will be required of each patient in order to participate in the clinical trial, including the number of doctor visits, tests, and the schedule of treatment.
Informed consent is used to protect a person enrolled in a clinical trial. It is an ongoing process between the patient and the health care team that allows the patient to ask questions, hear responses to his or her concerns, and keep up-to-date on any new information that is related to that specific clinical trial or treatment.
If English is not your main language, you can ask for the consent documents in languages other than English. Because joining a clinical trial is an important decision, you should ask the research team any questions  you may have about the study before you make a decision.
It is also a good idea to take the consent documents home and discuss them with family members or friends. Talking about your options can help you feel comfortable with your decision. If you decide to join the clinical trial, be sure to ask for a copy of the informed consent documents so you can review them at any time. Learn more about informed consent .
Freedom to withdraw from a clinical trial
Participating in research is always voluntary. You may stop participating in a clinical trial for any personal or medical reason at any timeâbefore the study starts, during the study, or during the follow-up period.
Clinical Trials 
National Cancer Institute: A Guide to Understanding Informed Consent