The short answer
A protocol is the detailed plan for a clinical trial. FDA says it states what the study will do, how, and why.
The protocol is the master plan for a clinical trial.
It defines who can join through eligibility criteria.
An institutional review board (IRB) reviews and approves the plan.
Informed consent is how you learn the risks and benefits before you decide.
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The simple version
A trial protocol is the detailed plan for a clinical trial. FDA says it states what the study will do, how it will be done, and why it is being done.
Who can join
The protocol includes eligibility criteria. FDA defines these as characteristics set by the research investigator, based on the safety and effectiveness of the treatment, to decide whether a patient can enroll.
Who writes it and who reviews it
NCI says the principal investigator writes the protocol and submits it for approval by an institutional review board (IRB). FDA describes an IRB as a group of scientists, doctors, clergy and patient advocates that reviews and approves the plan.
Why it matters to you
If you join, the protocol shapes what the study does with you. Informed consent is the process where you are given key information, including possible risks and benefits, so you can decide whether to take part. NCI says research nurses help with this process. You can ask for the parts of the protocol that affect you to be explained in plain language.
What to ask before you join
- Can you explain the parts of the protocol that describe my treatment and testing schedule?
- What is the trial's main question?
- What happens if the plan changes while I am enrolled?
- Which IRB reviewed and approved this trial?
Sources
- FDA, Patient-Friendly Language for Cancer Clinical Trials (opened 2026-10-02).
- NCI, How Clinical Trials Work (opened 2026-10-02).
Common questions
What is a trial protocol?
FDA describes a protocol as the detailed plan of how a new drug will be studied. It states what the study will do, how it will be done, and why.
Why does it matter to me?
It sets the rules for the study, including the eligibility criteria that decide whether you can enroll. Ask your research team which parts apply to you.
Who reviews the protocol?
FDA describes an institutional review board (IRB) as a group of scientists, doctors, clergy and patient advocates that reviews and approves the detailed plan for a clinical trial. NCI says the principal investigator writes the protocol and submits it for IRB approval.
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Written by: Cancer ExplainedSources last checked: 2026-07-14 what this meansLast updated: 2026-10-02Next planned review: 2027-01-14
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How this page was created
Cancer Explained does not originate medical claims. Every page restates guidance already published by the National Cancer Institute, the CDC, the USPSTF and the FDA, in plain language, with the source cited so you can check the original yourself. AI does the translating and organizing; automated checks test claims, citations, clarity and safety before anything publishes, and this is translation and navigation, not clinical judgment. Nothing here is personal medical advice, and no page can account for your particular situation.
Editorial status: Source checked — This page was written with AI assistance and then compared with the sources listed on it, looking for statements those sources do not back up. That check is not a sentence-by-sentence record and can miss errors. It is not a medical review, and it does not confirm the page is complete or right for your situation.
Human medical review: not completed. Pages here are not signed off by a clinician before they publish. That is not an oversight we are quietly working around: we restate published guidance and cite it, so the authority belongs to the source rather than to us, and every page names where its claims come from — you can verify us instead of trusting us. Where a volunteer clinician has reviewed a page, their name and credentials appear on it; where no name appears, no clinician has checked it. We are glad to have reviewers and are recruiting them, and we do not hold pages back waiting for one. Use this site to understand your situation and to ask better questions of the people treating you.
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