ABSTRACT
Introduction Cancer cells are dependent on blood vessels for growth and metastases. They cannot survive more than 200 µm away from an existing blood vessel, and tumors rarely exceed 2-3 mm3 without neovascularization. This phenomenon is called angiogenesis and corresponds to the development of new capillaries from existing vessels and the creation of new vessels from circulating endothelial progenitor cells. Under normal conditions, blood vessels remain quiescent, and angiogenesis occurs only in certain physiological (ovulation, menstrual cycle, pregnancy, and wound healing) or pathological processes (cancer, inflammation, and retinopathy). Numerous factors control angiogenesis. Advances in the understanding of angiogenesis have led to the development of anti-angiogenic therapies (blocking pro-angiogenic or miming anti-angiogenic natural factors) that show efficacy in clinical practice.
