ABSTRACT
Experimentation is an important resource for therapeutic and prevention research in the
era of molecular epidemiology. It is understood that well-executed clinical trials can add
greatly to our understanding of the impact of exposures on risk and of treatment on
disease outcome. Trials add significantly to our understanding of genetic variability; this
variability can predict or determine risk or treatment outcome; it can also be critical,
interacting with exposure, predicting risk, and with treatment, predicting outcome.
