Behavior of tumors under nonstationary therapy

We present a model for the interaction dynamics of lymphocytes-tumor cells population. This model reproduces all known states for the tumor. Further, we develop it taking into account periodical immunotherapy treatment with cytokines alone. A detailed analysis for the evolution of tumor cells as a function of frequency and therapy burden applied for the periodical treatment is carried out. Certain threshold values for the frequency and applied doses are derived from this analysis. So it seems possible to control and reduce the growth of the tumor. Also, constant values for cytokines doses seems to be a successful treatment. (C) 2003 Elsevier Science B.V. All rights reserved.