is the process through which a tumor supports its growth by creating its own blood supply
So now you know how cancer spreads around the body and also how it is actually difficult to do so. 'Metastasis' refers to the spread of cancer cells around the body. In order for this to occur, it's very important for cancer cells to start the process of angiogenesis, or the process by which new blood vessels form. They do so by secreting chemicals such as VEGF, or vascular endothelial growth factor, in order to 'entice' the blood vessels to grow branches towards the tumor site.