**2.7 Metastasis and angiogenesis**

Formation of new blood vessels from pre-existing vessels, angiogenesis, and augment metastatic colonization. Angiogenesis is essential for metastasis so that tumor cells get oxygen and nutrients as tumor cells exceed a minimum size, nutrients and oxygen can no longer reach through diffusion. By the same token, metabolism end products (lactate, ammonia, and lactate) cannot diffuse easily [3].
