Clinical trials are research studies in which people help doctors find ways to improve health and cancer care. Each study tries to answer scientific questions and find better ways to prevent, diagnose, or treat cancer.

Why are there clinical trials?
A clinical trial is one of the final stages of a long and careful cancer research process. Studies are done with cancer patients to find out whether promising approaches to cancer prevention, diagnosis, and treatment are safe and effective.

What are the different types of clinical trials?

		Treatment trials test new treatments (like a new cancer drug, new approaches to surgery or radiation therapy, new combinations of therapy, or new methods such as gene therapy).
		Prevention trials test new approaches, such as medicines, vitamins, minerals, or supplements that may lower the risk of a certain type of cancer. These trials look for the best way to prevent cancer in people who have never had cancer or to prevent cancer from coming back or a new cancer from occurring in people who already have cancer.
		Screening trials test the best way to find cancer, especially in its early stages.
		Quality of Life trials explore ways to improve comfort and quality of life for cancer patients.

What are the phases of clinical trials?
Most clinical research that involves the testing of a new drug progresses in an orderly series of steps, called phases. Phases allow researchers to ask and answer questions in a way that results in reliable information about the drug while protecting the patients. Clinical trials are usually classified into one of four phases:

		Phase I trials: These studies determine the best and safest way to give a new treatment (by mouth, injected into the blood, or injected into the muscle), how often, and at what dosage. Participants are a limited number of patients, sometimes as few as a dozen.
		Phase II trials: These studies continue to test the safety of the drug and begin to evaluate how well the new drug works. These trials also start to focus on various types of cancer who have had at least one standard treatment in the past.
		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 treatment. A participant will usually be assigned to the standard group or the new group at random (called randomization- which means by the flip of a coin). These trials often enroll large numbers of people and may be conducted at many doctor's offices, clinics, and cancer centers nationwide.
		Phase IV trials: These studies refine and improve management of side effects. Phase IV trials start after US Food and Drug Administration (FDA) approval of the drug for general use. Participants are patients who doctors prescribe the treatment.