The short answer
Clinical trials are research studies that test how well new medical approaches work in people. In cancer, they test new ways to find, prevent, and treat cancer, and to improve quality of life. People join for many reasons, and past trials are a big reason people with cancer are living longer today.
Clinical trials are research studies that test how well new medical approaches work in people.
Cancer trials test new ways to find, prevent, and treat cancer and to manage side effects.
Past clinical trials are a reason people are living longer today.
There are several types of trials: treatment, prevention, screening, and supportive/palliative care.
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The full explanation.
The simple version
Clinical trials are research studies that test how well new medical approaches work in people. In cancer research, clinical trials test new ways to find, prevent, and treat cancer. They also help doctors improve the quality of life for people with cancer by testing ways to manage the side effects of cancer and its treatment.
In short: a clinical trial is a carefully run study that tests a new medical idea in people.
Why clinical trials matter
Today, people are living longer lives thanks to the results of past cancer clinical trials. When you take part in a clinical trial, you add to our knowledge about cancer and help improve cancer care for people in the future.
People join clinical trials for many reasons:
- People living with cancer often join because they want to help future patients.
- People with certain risk factors want to help doctors learn how to prevent cancer.
- Healthy volunteers want to help doctors learn how to find cancer early.
People with cancer and healthy volunteers join trials to play a role in cancer research and move science forward to help others.
The main types of trials
There are several types of cancer clinical trials. Each type is designed to answer different research questions.
- Treatment trials. Most cancer clinical trials are treatment studies that involve people who have cancer. These trials test new treatments or new ways of using existing treatments.
- Prevention trials. These look at ways to prevent cancer. In most prevention trials, the people who take part do not have cancer but are at high risk of developing it, or they have had cancer and are at high risk of a new cancer.
- Screening trials. The goal is to test ways to find cancer before it causes symptoms, when it may be easier to treat.
- Supportive care / palliative care trials. These look at ways to improve the quality of life of people with cancer, especially those who have side effects from cancer and its treatment.
In short: different kinds of trials answer different questions, from prevention to treatment to comfort and quality of life.
Learning more
If you are interested in clinical trials, your healthcare team can help you understand your options and where to look. Every trial is different, so it helps to ask questions and take your time.
Words to know
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Common questions
What is a clinical trial?
Clinical trials are research studies that test how well new medical approaches work in people. In cancer research, they test new ways to find, prevent, and treat cancer. They also help doctors improve quality of life by testing ways to manage the side effects of cancer and its treatment.
Why are clinical trials important?
Today, people are living longer lives thanks to the results of past cancer clinical trials. When you take part in a trial, you add to what is known about cancer and help improve cancer care for people in the future.
Why do people join clinical trials?
People join for many reasons. People living with cancer often join because they want to help future patients. People with certain risk factors want to help doctors learn how to prevent cancer. Healthy volunteers want to help doctors learn how to find cancer early. All of them help move science forward to help others.
What are the main types of cancer clinical trials?
There are several types. Treatment trials test new treatments or new ways of using existing ones. Prevention trials look at ways to prevent cancer. Screening trials test ways to find cancer before it causes symptoms. Supportive or palliative care trials look at ways to improve quality of life for people with cancer.
Do you need to have cancer to join a clinical trial?
Not always. Most cancer trials are treatment studies that involve people who have cancer. But prevention trials often involve people who do not have cancer but are at high risk, and screening trials may involve healthy volunteers.
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Sources last checked: 2026-07-21 what this meansLast updated: 2026-07-21Next planned review: 2027-01-21
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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. We do not employ clinicians and do not intend to — our work 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 checked line by line against the sources listed on it. That confirms the sources support what the page says. 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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