Clinical Trials

How are clinical trials conducted?

Clinical trials testing new treatments are carried out in phases.

Phase I - Is the Treatment Safe?

When doctors are developing a new drug, the first step is to determine the maximum safe dose of a drug that can be administered. This needs to be done before any determination is whether the drug is effective (Phase II – See Below). Radiation phase I trials are a little different since radiation oncologists already know that the standard doses of radiation are effective. Phase I radiation trials attempt to increase the dose of radiation above that which is given under standard conditions, with the hope of increasing tumor control.

Phase II - Does the Treatment Work?

In a phase II radiation study, radiation oncologists are trying to establish if the new treatment seems to show enough promise in terms of shrinking the tumor that it is worth testing against the standard therapy in a phase III trial.

Phase III - Is the Treatment Better?

Phase III trials compare the new treatment are against the current standard therapy and randomly assign patients into one of the two groups.

Phase IV - Are There Better Ways to Use the Treatment?

In this final step, treatments are tested to make sure they are safe and work well over a long period of time. This phase most often occurs once the new treatment has been approved for standard use. Anywhere from several hundred to several thousand people are enrolled in phase IV trials.

Only you can make the decision about whether or not to participate in a clinical trial. Before making your decision, learn as much as possible about your cancer and the clinical trials that may be available to you. Your radiation oncologist can answer many of your questions if you are considering a trial or contact the National Cancer Institute at 1-800-4-CANCER or www.cancer.gov.