Clinical studies, also known as clinical trials, are research studies in which people help doctors find better ways to prevent, diagnose or treat medical conditions, including cancer. The results of clinical studies for many conditions — including breast, colon and childhood cancers — have allowed people to live much longer and more productive lives.

Why are there clinical studies?

A clinical study is one of the final stages of a long and careful cancer research process. Cancer patients who participate in clinical studies and providing a valuable benefit to cancer research by helping to determine the effectiveness of new approaches to cancer prevention, diagnosis and treatment.

What are the different types of clinical studies?

  • Treatment trials test new treatments (like a new cancer drug, new approaches to surgery or radiation therapy, new combinations of treatments, or new methods such as gene therapy).
  • Prevention trials test new approaches, such as medicines, vitamins, minerals or other supplements that doctors believe 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 have already had cancer.
  • Screening trials test the best way to find cancer, especially in its early stages.
  • Quality of Life trials (also called Supportive Care trials) explore ways to improve comfort and quality of life for cancer patients.

What are the phases of clinical studies?

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: 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 it should be given and in what dosage it should be given. A phase I trial usually enrolls only a small number of patients, sometimes as few as a dozen.
  • Phase II: 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: 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.

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.

Source: National Cancer Institute