Qualitative analysis of tumor growth model under antiangiogenic therapy ‐ choosing the effective operating point and design parameters for controller design

Every therapy that fights against cancer aims to reduce the tumor volume as far as possible. However, the price of low tumor volume has to be paid twice: as financial cost and also as side effect cost. In this article, we present qualitative correlation between the steady‐state tumor volume and inhibitor serum concentration based on the tumor growth model. Assuming standard state feedback, we present qualitative correlation between the steady‐state tumor volume and the parameters of the controller. In case of using an observer, we specify the steady‐state tumor volume and the expression for determining the steady‐state error of the state observer. We apply a limit for the state feedback to guarantee the stability of the closed‐loop system and the positivity of the control signal. The controller parameters depend on the applied operation point where the nonlinear system was linearized. We have investigated the effect of the operation point via simulations, and we present a quantitative theory for choosing the effective operating point