Are the Phenotypes of Preneoplastic Lesions of Significance for Cancer Prevention? 1. Liver

Preneoplastic lesions have been described for most major sites of human tumour development. They appear to be sharecharacteristics like monoclonality, induction by all classes of carcinogens and some quantitative relationship to actualtumours. Extensive studies of preneoplasia in the liver of the rat has indicated that a directed shift in phenotype occurs,commensurate with greater physiological emphasis on growth potential. One characteristic change is increase in the keyenzyme of the pentose phosphate pathway, glucose 6 phosphatase dehydrogenase as well as elevation in glycolysis, reductionof gluconeogenesis. In general, the changes observed in preneoplastic liver lesions appear reminiscent of the effects ofinsulin or other hormones on hepatocytes, pointing to possible application of specific inhibitors for cancer chemoprevention.