Effect of vascularization on glioma tumor growth

As a tumor grows beyond a critical size and becomes nutrient-limited, it requires delivery of new resources and removal of waste products. The development of a new vascular network to support tumor growth allows then oxygen and nutrient to reach tumor cells. In this chapter, we study the influence of vascularization on tumor growth with the help of a combination of in vivo data from implanted xenografts of U87 MG in nude mice brain and a mathematical model. We identify three different growth regimes occurring during the tumor development and investigate the interplay among these regimes and the vascularization dynamics. Our results show that the initial (avascular) tumor growth is followed by a transient regime characterized by over-vascularization, before relaxing to a dynamics where the tumor radius increases linearly in time. Our model suggests that this linear regime corresponds to the equilibration of vascularization and metabolic dynamics. We use our findings to discuss the initiation of angiogenic processes and the implications for anti-angiogenic therapy.