ABSTRACT
In the last chapter, characteristics and mechanisms of the early stages of neoplastic development-initiation and promotion-were presented as being the result of cellular and molecular changes induced by specific carcinogenic agents. However, one must not forget that a neoplasm, by definition, develops within a complete, viable, multicellular organism. In a later chapter (Chapter 14) the “transformation” of normal cells to cells having distinctive characteristics while cultured in vitro is considered. However, in order to relate such transformation in vitro to the neoplastic process in vivo, the whole animal must be utilized as a testing arena in order to determine the neoplastic potential of cells that have been altered in culture.
