[Cancer as a function of disposition, exposure and age].

Essential parameters in carcinogenesis are the genetic and extragenetic disposition of an individual, its exposure to chemical, physical or viral influences in the environment as well as its age as the time that is needed to induce cancer. Cancer prevention seems only possible by reducing the exposure. It will be discussed whether the increase in life expectancy has become so important during the past decades that it compensates all efforts of reducing the exposure.