Summary

Experiments in animals have demonstrated that regulatory factors are able to stop or delay tumor growth. These regulators are present in embryos of ovipari and in pregnant uteri of mammals, when differentiative processes are occurring and they are capable of activating anti-oncogene p53 in different tumor cells in vitro. The use of these regulatory network in human therapy of cancer has demonstrated good effects on performance-status and on progression of disease. These regulators are probably specific for each kind of tumor. Cancer represents different deseases in which are present different changes: activation of proto-oncogenes or, more frequently, of oncogenes, repression or mutation of anti-oncogenes, production of growth factors. Practically the program of cell differentiation (or a part of this program) is cancelled in tumor cells. This allowed the expression of genes of multiplication, repressed in the course of cell differentiation: in this sense cancer cells are similar to embryonic mutated cells. Now if the therapeutic approach to cancer is to regulate the multiplication of cells and normalize the process, it is impossible to achieve this aim, by using single molecules. To rewrite the cancelled program in cancer cells and thus to normalize the process it is necessary to use the informative network of cell differentiation. This means that we have to change the scientific paradigm and to shift the emphasis from reductionism to complexity.