This paper discusses the use of cancer incidence data in identification of cancer causation. Selective descriptive and analytical epidemiological studies were reviewed. These examples were taken primarily from Denmark, where the possibilities for epidemiological research are good due to the existence of many exposure and disease registers. Descriptive studies are still needed for a better understanding of cancer. Analytical studies of individual risk factors today often show relative risks of only 1.5 to 2, and these are difficult to translate into preventive recommendations.
Epidemiology still remains the best available tool for identification of risk factors.