The value of anti-angiogenics in breast cancer therapy

Tumor-induced angiogenesis supplies the tumor with nutrients and oxygen necessary to grow and provides tumor cells with a possibility to intravasate into blood vessels as first step of metastatic spread. In the last two decades, evidence has been accumulating that controlling tumor-associated angiogenesis might be a promising strategy against cancer growth. In breast cancer, a number of angiogenesis inhibitors have been investigated in clinical trials. The antibody against vascular endothelial growth factor (VEGF) bevacizumab has been approved for treatment of metastatic breast cancer in Europe. Although the mechanism of action is still under study, bevacizumab was also tested in other clinical settings of breast cancer treatment such as neoadjuvant and adjuvant therapy, as maintenance therapy, and in combination with both chemotherapy and other targeted agents. Other anti-angiogenic agents, such as oral tyrosine kinase inhibitors sorafenib, sunitinib, and pazopanib, were tested and have not yielded as promising results. In this chapter, we will review the current evidence and clinical relevance of anti-angiogenic treatment in early and metastatic breast cancer.