Angiogenesis in prostate cancer: biology and therapeutic opportunities.

Tumor growth is limited in size without the incorporation of new blood vessels. Tumor cells release soluble factors (angiogenic factors) that induce neovascularization and allow subsequent growth beyond 2-3 mm in diameter meeting the need for cellular uptake of oxygen and nutrients. This process is referred to as the 'angiogenic switch' and indicates the acquisition of an angiogenic phenotype. Tumor angiogenesis requires an imbalance between proangiogenic and antiangiogenic factors with formation of new vessels being a highly regulated process. In this review we discuss the mediators of angiogenesis, the strategies for manipulating angiogenic factors, and possible therapeutic applications with a special emphasis on prostate cancer.