Abstract
Apart from the so-called short-term or in vitro test and the animal experiment, epidemiology represents the third method for detecting carcinogenic effects. Epidemiological methodology constitutes the sole possibility of studying in man cancerous diseases and the influence of noxae suspected to be carcinogenic. The three main approaches of epidemiological research--descriptive, analytic, and experimental epidemiology--are confronted and their importance for tracking down cancer is explained by means of examples.