Tumor angiogenesis

Tumor angiogenesis is the growth of new blood vessels which is required for tumor growth and progression. Vascularization of the tumor occurs through a series of sequential steps before or during the multistep progression to neoplasia. Several events occur during the formation of new vessels including production of protease enzymes, unregulation of positive regulators of angiogenesis, and down regulation of negative regulators. In addition, tumor associated macrophage also influence angiogenesis by secreting enzymes, enzymes inhibitors and cytokines. Recent knowledge in tumor angiogenesis may have clinical implications in diagnosis and treatment. Quantification of microvessel density in tumor specimen correlates either metastasis or recurrence in many malignancies such as breast cancer and lung cancer. Therefore, assessment of tumor angiogenesis may serve as prognostic factors. Therapeutic applications include the development of new agents with antiangiogenic properties, vascular targeting drugs, antibody-based therapy, and gene therapy. Combination of antiangiogenic therapy with cytotoxic drugs may enhance antitumor activity. Moreover, the role of antiangiogenic therapy in adjuvant setting may provide and alternative approach to better cancer treatment in the near future.