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Key Terms to Know About Clinical Trials

Updated December 17, 2014

As you gather information on participating in a clinical trial, you may hear some unfamiliar terms. Here are ten key words to know as you do your research and talk with your healthcare team.

Arm: A treatment group within a clinical trial.

Clinical trial: A research study conducted in people.

Double-blinded trial: A study in which neither the participant nor the researcher or healthcare provider knows which treatment the participant is receiving.

Informed consent: A process that educates about a trial’s purpose, possible benefits and potential risks, rights of participants and more. After getting that information, prospective participants read, talk with a doctor or nurse and sign an informed consent document. Participants may withdraw consent at any time and for any reason.

Institutional Review Board (IRB): A group of medical providers and community members that evaluates and approves a study for safety before it begins and while it is going on. The IRB may change or stop the trial if problems arise or to make effective new treatment available sooner.

Phase: A research testing step. Learn more about phases.

Principal investigator: The researcher in charge of a clinical trial.

Protocol: The plan that describes what will happen in the trial and how it will be conducted.

Randomized study: A clinical trial in which a computer randomly assigns people for each arm, or branch, of the study.

Research nurse: The link between participant, doctor and the clinical trial who provides information and answers questions. The research nurse collects and reports data throughout the trial.

Read more about clinical trials and the providers who helped us write this page in our Guide to Understanding Breast Cancer Treatment Research Studies.