Quantitative selection constants.

The study of the genetics of human tumors produces numerical data concerning the frequencies of mutation of individual genes. These frequencies are dependent on a number of processes that act individually and differentially upon genes, and can in turn be conceptualized in quantitative terms to encompass the rates of random mutations within cells, the efficiencies of the evolution of initial mutations to produce the functional inactivation of genes, and selective pressures that act upon cellular populations. Some intuitive mathematical models can be used to organize and formalize our interpretation of the mutation rates of tumor-suppressor genes.