The clinical implications of angiogenesis in the treatment of cancer.

Angiogenesis, the formation of new blood vessels from pre-existing ones, is a very well controlled multistep process under physiologic conditions. It involves a balance between several positive and negative regulators. Pathologic angiogenesis, both excessive and insufficient, plays a role in the pathophysiology of many diseases including cancer. It has been proven that tumor growth and metastasis are angiogenesis-dependent. Endothelial cells and tumor cells also provide a mutual support to each other via the secretion of several substances. Targeting tumor blood vessels is a new approach to the treatment of cancer. Clinical trials are currently underway and the results appear to be very promising.