Three versions of the adenoma growth model.

N normal stem cells of colonic crypts are susceptible to a series of mutations with rates μ0 (K = 0), μ0, μ1 with intermediate stage S1 (K = 1) and μ0, μ1, μ2 with intermediate stages S1, S2 (K = 2) before they start adenoma growth by clonal expansion with rates α for symmetric division and β for differentiation, γ = α − β is the net rate of clonal growth; dashes lines pertain to the full MSCE model of carcinogenesis (not modeled in the present study), ν denotes the transforming mutation rate to cancer cells, which expand into clinically relevant tumors with net rate γc = αc − βc.