[Mechanisms of tumorigenesis].

In the etiology of human cancers mutational events, selective amplification of specific cellular sequences after treatment of cells with chemical and physical carcinogens, and viruses are discussed. In cancers of the anogenital tract it appears that these as well as possibly additional human cancers are caused by the persistence of specific viral genes and the failure of an intracellular surveillance system for such genes. The modification of host cell genes should primarily result from interactions with chemical and physical factors.