Stochastic processes often pose the difficulty that, as soon as a model devi- ates from the simplest kinds of assumptions, the differential equations obtained for the density and the generating functions become mathematically formidable. Worse still, one is very often led to equations which have no known solution and don't yield to standard analytical methods for differential equations. In the model considered here, one for tumor growth with an immunological re- sponse from the normal tissue, a nonlinear term in the transition probability for the death of a tumor cell leads to the...