The scientific basis of clinical trials: statistical aspects.

The objective of this paper is to delineate some of the advances in clinical oncology that have occurred since the 1950s in the context of methodological principles established by Dr. Emil J Freireich and colleagues. Four statistical aspects of the methodological developments in clinical trials are considered and illustrated by real examples: a quantitative approach to the design and analysis of clinical trials; the randomized controlled trial; the nonrandomized controlled trial; and the use of regression models in clinical studies.