An Introduction to Clinical Trials

There are several different kinds of clinical trials. Trials are designed to test cancer prevention, screening, treatment and methods to improve the quality of life for cancer patients. Clinical trials are performed to evaluate the safety and efficacy of potential cancer treatments. Enrollment in a treatment trial does not mean that the patient will only be taking an experimental treatment. Often new drugs or treatments are combined with current treatments/drugs to see if there is an added benefit to the patient.

Clinical trials of new drugs/treatments are divided up into three stages or phases. The goals of each phase are described below.

• Phase 0 trials are a relatively new type of trial.  They were introduced to speed up the process of drug devlopment. These small trials allow drugs to be tested earlier in their development.  Normal volunteers are exposed to small amounts of the drug to study the way the drug is metabolized and whether it interacts with its target in humans.⁽¹⁾
• Phase I trials are designed to test the safety of the drug in humans. The optimum dosing and route of administration may be examined in these studies. Often these trials are performed on only small groups of patients.
• Phase II trials are designed to extend the safety information of the treatment and to examine the efficacy of the treatment against one or a few cancer types.
• Phase III trials are usually much larger than the previous phases and involve many patients. In these studies, the trial drug/treatment is compared with the currently accepted treatment for a particular cancer.⁽²⁾

Below, watch cancer survivor Ginny Johnston's viewpoint on her choice to participate in clinical trials.

Watch the full Ginny Johnston interview

More information on this topic may be found in Chapter 16 of The Biology of Cancer by Robert A. Weinberg.

If you find the material useful, please consider linking to our website

1. Kummar S, Rubinstein L, Kinders R, Parchment RE, Gutierrez ME, Murgo AJ, Ji J, Mroczkowski B, Pickeral OK, Simpson M, Hollingshead M, Yang SX, Helman L, Wiltrout R, Collins J, Tomaszewski JE, Doroshow JH. (2008). Phase 0 clinical trials: conceptions and misconceptions. Cancer J. 14(3):133-7. [PUBMED]
2. NCI Clinical Trial Information Page [http://www.cancer.gov/clinical_trials/understanding/]