One of the dangerous death-causing diseases called cancer can be cured by exploiting a renowned technique called chemotherapy. Nowadays, to find the optimal drug rate injection the controller-based technique is exploited therefore, the treatment has increased sufficiently. In this paper, a new robust controller which influences the dosage of drug besides the parameter estimation is presented in this paper. A new adaptive square-root unscented Kalman filter (ASr-UKF)is developed in this work. In reality, by exploiting the existing difference function, the error is calculated and it is deployed for the updating procedure of the proposed method in the conventional methods. On the basis of the prior error function, the updating process is performed while scaled to a nonlinear environment. Moreover, to update the process, the scaling factor is developed that includes enhancement in the historical error. At last, the developed controller performance is considered with the conventional methods that entail the suitable effect of drug dosage injection on normal, tumor and immune cells. In addition, it is seen that the adopted model possesses the capability to calculate tumor cells by means ofa superior accuracy rate