The evaluation of the efficacy and safety of a clinical tool, be it a diagnostic technique, a preventive methodology, or a therapeutic intervention, is an im portant responsibility of physicians. The history of medicine is characterized by the authoritarianisms of teachers and of organizations giving way to the clinical experience of physicians; authoritarian dictum was replaced by case report and then by case series. As physicians learned to substitute the analysis of data for the inconsistencies of dictums and anecdotes, the problems of the case series as an investigative tool became more evident: patient selection criteria, measurements of outcome, significance of results, and extrapolation of conclusions to the community of patients. In response to these issues, the methodology of the controlled clinical trial has evolved and with it the instru ments of study design and of biostatistics as aids to study design and data analysis. The medical - surgical armamentarium has evolved from being dependent solely upon the observations and conclusions of a skilled clinician to being constructed upon the systematic collection and evaluation of data by a team of skilled clinicians and their statistical colleagues: this is the controlled clinical trial. During the past two decades, the evaluation of clinical approaches to pre vention and therapy has become particularly important to clinicians concerned with nervous system dysfunction. There has been and continues to be an explosion of information from the basic neurosciences and from the applica tion of biotechnology to the nervous system."

When asked why he robbed banks, an astute and success ful criminal is said to have replied "Because that's where the money is kept." Why study patients with multiple primary cancers? The answer follows the same practical approach. Because the intensive investigation of such patients is very likely to yield data useful to both the clinical and research on cologist. Studies of this problem provide an immediate return for the clinician responsible for the care of cancer patients. With improved forms of therapy, these individuals are enjoying longer periods of survival. One important factor in maintaining increased survival is the early detection and treatment of new primary tumors which may develop. Analyses of multiple primary malignancies serve as a guide to the probable anatomic location of a subsequent primary and help define characteristics of the individual at high risk for multiple primary cancer. But just as treatment may improve the life of the cancer patient, it may also increase the risk of a subsequent malignancy. Studies of multiple primaries provide an efficient means for quantifying potentially harmful effects of current therapeutic modalities."

The evaluation of the efficacy and safety of a clinical tool, be it a diagnostic technique, a preventive methodology, or a therapeutic intervention, is an im portant responsibility of physicians. The history of medicine is characterized by the authoritarianisms of teachers and of organizations giving way to the clinical experience of physicians; authoritarian dictum was replaced by case report and then by case series. As physicians learned to substitute the analysis of data for the inconsistencies of dictums and anecdotes, the problems of the case series as an investigative tool became more evident: patient selection criteria, measurements of outcome, significance of results, and extrapolation of conclusions to the community of patients. In response to these issues, the methodology of the controlled clinical trial has evolved and with it the instru ments of study design and of biostatistics as aids to study design and data analysis. The medical - surgical armamentarium has evolved from being dependent solely upon the observations and conclusions of a skilled clinician to being constructed upon the systematic collection and evaluation of data by a team of skilled clinicians and their statistical colleagues: this is the controlled clinical trial. During the past two decades, the evaluation of clinical approaches to pre vention and therapy has become particularly important to clinicians concerned with nervous system dysfunction. There has been and continues to be an explosion of information from the basic neurosciences and from the applica tion of biotechnology to the nervous system."