What Are Clinical Trials?
Cancer clinical trials are research studies in which people help doctors find ways to improve health and cancer care. Studies involve working with cancer patients to find out whether promising approaches to cancer prevention, diagnosis, and treatment are safe and effective.
Many cancer clinical trials examine whether a new drug or device is safe and effective for people to use. Some compare existing treatments to determine which is better. The current, approved treatments are called the "standard treatments." Sometimes cancer clinical trials are used to study different ways to use the standard treatments so they will be more effective, easier to use and/or decrease side effects.
What are the types of clinical trials?
- Prevention trials test new approaches, such as medications, vitamins, or other supplements, that doctors believe may lower the risk of developing a certain type of cancer. Most prevention trials are conducted with healthy people who have not had cancer. Some cancer clinical trials are conducted with people who have had cancer and want to prevent recurrence (return of cancer), or reduce the chance of developing a new type of cancer.
- Screening trials study ways to detect cancer earlier. They determine whether finding cancer before it causes symptoms decreases the chance of dying from the disease. These trials involve people who do not have any symptoms of cancer.
- Diagnostic trials study tests or procedures that could be used to identify cancer more accurately. They usually include people who have signs or symptoms of cancer.
- Treatment trials are conducted with people who have cancer. They are designed to answer specific questions about, and evaluate the effectiveness of, a new treatment or a new way of using a standard treatment. These cancer clinical trials test many types of treatments, such as new drugs, vaccines, new approaches to surgery or radiation therapy, or new combinations of treatments.
- Quality-of-life (also called supportive care) trials explore ways to improve the comfort and quality of life of cancer patients and cancer survivors. These trials may study ways to help people who are experiencing nausea, vomiting, sleep disorders, depression, or other effects from cancer or its treatment.
- Genetics studies are sometimes part of another cancer clinical trial. The genetics component of the trial may focus on how genetic makeup can affect detection, diagnosis, or response to cancer treatment.
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What are the phases of cancer clinical trials?
Most clinical research that involves the testing of a new drug progresses in an orderly series of steps, called phases. Most cancer clinical trials are classified into one of four phases:
- Phase I trials: These first studies evaluate how a new drug should be given (by mouth, injected into the blood, or injected into the muscle), how often, and what dose is safe. A phase I trial usually enrolls only a small number of patients, sometimes as few as a dozen.
- Phase II trials: A phase II trial continues to test the safety of the drug, and begins to evaluate how well the new drug works. Phase II studies usually focus on a particular type of cancer.
- Phase III trials: These studies test a new drug, a new combination of drugs, or a new surgical procedure in comparison to the current standard. A participant will usually be assigned to the standard group or the new group at random. Phase III trials often enroll large numbers of people and may be conducted at many doctors' offices, clinics, and cancer centers nationwide.
- Phase IV trials: After a treatment has been approved and is being marketed, the drug's maker may study it further in a phase IV trial. The purpose of phase IV trials is to evaluate the side effects, risks, and benefits of a drug over a longer period of time and in a larger number of people than in phase III clinical trials. Thousands of people are involved in a phase IV trial.
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