NONLINEAR DYNAMICS OF IMMUNOGENIC TUMOR-GROWTH

The time delayed cytotoxic T-lymphocyte response to the tumor growth h as been analysed on the basis of discrete approximation (2-dimensional map). The growth kinetics has been described by logistic law with gro wth rate being the bifurcation parameter. Increase in the growth late results in instability of the tumor state and causes period-doubling b ifurcations in the immunity + tumor system. For large values of tumor growth rate a strange attractor has been observed. The model predicts the metastable state when time series data of the immune and tumor cel ls are chaotic and confusing which may be caused not by external (medi cal) factors but lather by internal substrate competition.