Immunotherapy plays a major role in tumour treatment, in comparison with other methods of dealing with cancer. The Kirschner-Panetta (KP) model of cancer immunotherapy describes the interaction between tumour cells, effector cells and interleukin-2 which are clinically utilized as medical treatment. The model selects a rich concept of immune-tumour dynamics. In this paper, approximate analytical solutions to KP model are represented by using the differential transform and Adomian decomposition. The complicated nonlinearity of the KP system causes the application of these two methods to require more involved calculations. The approximate analytical solutions to the model are compared with the results obtained by numerical fourth order Runge-Kutta method.