2 HIT AND MULTIPLE HIT THEORIES OF CARCINOGENESIS

Graphical analysis of the death rates at five year age intervals for gastric cancer in women show a quantitatively and qualitatively better fit with the mathematical expression derived for a multi-stage theory of carcinogenesis than with that derived for a two stage theory. Cohort analysis of the data collected for England and Wales confirms this finding. The pathological bases for the two theories are considered and it is shown that the two are not mutually exclusive but that the stage of initiation and the stage of promotion may each be the consequence of a number of discrete changes in cell structure and function. Illustrations are cited to show that after carcinogenesis has occurred further discrete changes in the now neoplastic, autonomous cells can be identified with the comparatively crude methods of light microscopy. © 1969, The British Empire Cancer Campaign for Research. All rights reserved.