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 share characteristics like monoclonality, induction by all classes of carcinogens and some quantitative relationship to actual tumours. 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 key enzyme of the pentose phosphate pathway, glucose 6 phosphatase dehydrogenase as well as elevation in glycolysis, reduction of gluconeogenesis. In general, the changes observed in preneoplastic liver lesions appear reminiscent of the effects of insulin or other hormones on hepatocytes, pointing to possible application of specific inhibitors for cancer chemoprevention.