What Is a Clinical Trial?
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 to find better ways to prevent,
diagnose, or treat cancer.
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
Most clinical research that involves the testing of a new drug progresses in an orderly series of steps, called phases. This allows researchers to ask and answer questions in a way that results in reliable information about the drug and protects the patients. Most clinical trials are classified into one of three phases:
Phase I trials: These first studies in people 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
randomization 10). Phase III trials often enroll large numbers of people and may be conducted at many doctors' offices, clinics, and cancer centers nationwide
In addition, 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.p>