Figure 3

The evolution of normal cells and tumor cells during the phases of therapy. The drug is considered to be dynamic and its concentration diffuses exponentially over time. u₀ is the initial value of the drug and d is the decaying rate, and m is linked to pharmacokinetics and considered to be 1 in this study. The drug does not have any effect on normal cells, a _N (1 - e^mu) = 0, a _T = 0.1. First row: The evolution of normal and tumor cells is simulated for different drug decaying rates. u₀ = 1, and untreated (blue), d = 0.1 (red), 0.5 (green), 1 (black), and 2 (brown). As can be seen, the system tends to behave as untreated as the decaying rate increases. Second row: Same parameters in the first row except the initial value of the drug is increased, u₀ = 3, which maintains the diffusion behavior of the drug leading to slower growth for the tumor cells and a delay in entering the inhibition phase for the normal cells. The rest of the parameters are similar to the common parameter introduced in Figure [1].