ABSTRACT
Rather than writing a review with a limited scope, we attempted to survey the span of medical and molecular biology research in the field of oncology during the last six decades: from the
early breakthroughs in viral oncology and the novel notions of virus and viral cancer (onc) genes; to
the role of DNA cancer viruses and C retroviruses in experimental carcinogenesis; through the
discovery of cellular oncogenes and the biology of growth factors; to the expansion of the concept of
oncogene and its types; and, finally, to the realization that cancer is a multiplicity of different disorders that appear to arise through nonviral auto-oncogenic processes involving adaptive changes and
epigenetic responses to cancer-promoting pressures in the external and internal environment of the
organism. Throughout, we have searched for the integration of an oncogenic vector with different
degrees of transformation, seeking the commonality of proliferative disorders, somatic cancer and
leukemia. We re-examine what separates transformation, benign and malignant, from differentiation,
and how their reversible switch deploys graded responses related to states of hypersensitivity to, or
independence from, key physiological growth factors.
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