Carcinogenesis

1. Concepts on the Causal Genesis of Human Intestinal Tumors The action of chemical substances has a significant role in the genesis of human tumors. It is assumed that most human tumors are induced by exogenous chemical noxae (Schmahl, 1970;Heidelberger, 1975; and others). In the course of intensive efforts to discover the principles of tumor etiology, important insights have resulted in recent y...