Illustration of angiogenesis. When a tumour forms, it is isolated and produces substances (VEGF) which stimulate the production of small blood vessels from neighbouring vessels. A new vascularisation surrounds the tumour and nourishes it, allowing it to grow. Antiangiogeneses medecine will block the process by trapping the VEGF and therefore destroying the vascularisation of the tumour. This treatment improves the efficiency of chemotherapy with which it is always associated.