PRESENT KNOWLEDGE ABOUT SYNCARCINOGENESIS IN EXOGENOUSLY INDUCED-TUMORS

Little is known about syncarcinogenic effects of occupational and envi ronmental substances although it is supposed that different exogenous factors may play critical roles in the development of many human tumor s. Epidemiologic results prove syncarcinogenesis for asbestos exposure and smoking (lung cancer), radon exposure and smoking (lung cancer), exposure to aromatic amines and smoking (bladder cancer) and alcohol a buse and smoking (oral, larynx and oesophagus cancer). Animal experime nts point to additive effects in carcinogenesis for different nitrosam ines and substances like benzo(a)pyrene, carbon tetrachloride, ethanol , vinyle chloride and ionising radiation. It can be concluded from mod ern concepts of carcinogenesis that syncarcinogenic mechanisms may not only result from genotoxicity but also from influences on cell prolif eration and mitogenesis as well as toxico-kinetics, DNA repair, interc ellular communication, immune systeme and hormonal effects. New method s of molecular epidemiology seem very promising to study syncarcinogen ic effects in animals and humans.