Clinical Trials: Why are They Important?

by Stuart Lessin, M.D., Fox Chase Cancer Center

A clinical trial is a carefully designed study to test the effectiveness of a new drug or disease treatment. Clinical trials are designed to answer three basic questions about a new treatment:

1) is it safe?
2) Does it work?
3) Does it work better than other treatments?

Usually, three separate clinical trials are designed to answer these basic questions.
A phase I clinical trial tests new agents that are administered to humans for the first time. The main objective of a phase I trial is to test for safety, that is, what types of side effects do patients experience and what is the safest dose. For new cancer treatments, phase I trials recruit patients with advanced stages that have not been successfully treated with other therpies.

Phase II clinical trials test how well a new treatment works, at doses determined from the phase I study. Depending on the nature of the new treatment and the cancer being studied, phase II trials may include one or more stages of cancer patients.

Phase III clinical trials compare a new treatment with other established treatments, to determine if the new treatment produces better responses rates. To gain Food and Drug Administration approval, a new cancer treatment must complete all three phases and clearly demonstrate that it is safe (with tolerable side effects) and effective in treating a particular cancer.

The design of a clinical trial, referred to as a protocol, is thoroughly reviewed by one or more panel of experts. An internal review board (IRB), a committee of health care providers, scientists and lay persons carefully review all human safety and ethical issues and must provide the final approval, before a clinical trial can begin. A clinical trial is continuously monitored and reviewed annually by the IRB to ensure that it is conducted properly and that the tested treatments are safe.

Where to find more information:

NCI's Cancer Information Service (CIS): The CIS provides toll-free access to trained cancer information specialists at 1-800-4-CANCER. Additional information is available at

NCI's Clinical Trials Website: This website enables visitors to search for clinical trial results, developments, ongoing clinical trials, general clinical trial information, and more. The U.S. National Institutes of Health, through its National Library of Medicine, has developed to provide patients, family members and members of the public current information about clinical research studies. This website contains information on cancer and other conditions.

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