Marvin Zelen, PhD

The modern era of therapeutics in cancer is dominated by clinical data arising from cancer clinical trials. This reliance on clinical trial methodology to generate scientific data on the value of interventions not only has been adopted by the oncology community but is true for those working with all chronic diseases. In the United States, efforts to find interventions for acquired immunodeficiency syndrome (AIDS) are principally relying on clinical trials. Applications for drug approval to the US Food and Drug Administration (FDA) can only be made on the basis of scientific evidence generated by clinical trials. The development and widespread acceptance of clinical trials is one of the major conceptual advances in experimental therapeutics made during the latter half of the twentieth century.

A clinical trial is defined as an experiment on humans being carried out in order to evaluate one or more potentially beneficial therapies. The clinical investigator is assumed to have control of both the therapies being evaluated and the patient population to which these therapies are administered.

The basic ideas that are associated with clinical trials have been discussed for at least 150 years. An important intellectual landmark is the treatise Essays in Clinical Instruction, written by the French physician P.C.A. Louis in 1834.1 He advocated the use of the “numerical method” to study the benefits of therapy. His view was that only with “counting” is it possible to learn about the scientific basis of medicine; however, “counting is not easy. It is necessary to account for the different circumstances of age, ha ha, temperament, physical condition, natural history of the disease, and errors in giving therapy.” Louis wrote: “The only reproach which can be made to the Numerical Method is that it offers real difficulties in its execution. . .this method requires much more labor and time than the most distinguished members of our profession can dedicate to it.” Louis' comments are as appropriate today as when he wrote them.
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