Before revision:  Microscopic feedback control therapies are designed to influence the natural tumour growth and to mitigate the risk factors involved in big sized tumours. Several numerical examples illustrate the effectiveness of the approach .
After revision:  Microscopic feedback control therapies are designed to influence the natural tumour growth and to mitigate the risk factors involved in big sized tumors. We further show that under a suitable scaling both the free and controlled growth models correspond to Fokker--Planck type equations for the growth distribution with variable coefficients of diffusion and drift, whose steady solutions in the free case are given by a class of generalized Gamma densities which can be characterized by fat tails. In this scaling the feedback control produces an explicit modification of the drift operator, which is shown to strongly modify the emerging distribution for the tumor size. In particular, the size distributions in presence of therapies manifest slim tails in all growth models, which corresponds to a marked mitigation of the risk factors. Numerical results confirming the theoretical analysis are also presented .