The effect of tissue-specific growth patterns of target stem cells on the spectrum of tumours resulting from multistage tumorigenesis.

A multistage mathematical model of tumorigenesis has been developed to explore the effects of target cell growth pattern on the proportions of tumours deriving from different tissues (the tumour spectrum). Analytical modelling techniques have shown that the effect of the target cell growth pattern on the tumour spectrum also depends on the number of stages (gene mutations) necessary for malignant change in cells of each tissue type. This suggests the existence of temporal “windows of opportunity” for tumours of different types in relation to stage number and growth kinetics. Models of this kind are applicable to cancer-prone transgenic (e.g. p53 deficient) mice, where homozygotes and heterozygotes differ in one carcinogenic stage, and differ also in the spectrum of tumours observed. Generally, tumours deriving from target stem cells which are developmentally short-lived will arise more frequently in homozygotes than heterozygotes. Such models may also be applicable to human syndromes (e.g. Li-Fraumeni) in which susceptibility to cancer is inherited.