Tumour angiogenesis and anti-angiogenic therapy

The great majority of primary tumours are benign that are harmless to their hosts. So the chances of death caused by the benign tumour are very less or rare. Most of the cancer related deaths are caused due to metastatic property. Cancer metastasis is a complex multistep phenomenon which is the exclusive property of malignant tumours. During metastasis cancer cells leave the original tumor site (i.e. primary tumour) and migrate to other parts of the body via the bloodstream, or the lymphatic system. The new tumour in a distant target organ is known as a secondary or metastatic tumour. In most cases, patients with localized primary tumours have better prognoses than those with metastatic tumour. Metastatic process and tumour growth are angiogenesis dependent. This type of angiogenesis is characterized by abnormal vascular development. In this condition, the blood vessels created are not exactly the same as normal blood vessels. They are not organized into definitive venules, arterioles and capillaries. They are leakier than normal vessels. The complexity of the angiogenic process, which involves both positive and negative regulators, provides a number of targets for therapy.