Angiogenesis in breast cancer

This chapter reviews the basic concepts of tumor angiogenesis as well as the role of measuring intratumoral micro vessel density as an independent prognostic indicator for predicting tumor growth and metastasis, not only in breast carcinoma, but also in other solid tumors. For a tumor to growth, the tumor cells must proliferate and the benign host tissues must form around the tumor cells. Moreover, to metastasize a variety of critically important interactions must occur between tumor cells and the non-neoplastic vasculature, immune system, and connective tissues. Tumor angiogenesis refers to the growth of new vessels toward and within the tumor. This tumor neovascularization is caused by factors released by the tumor cells and/or associated inflammatory cells. Initially, many investigators thought that tumor hyperemia resulted from expansion of pre-existing vessels [1,2], but during the last two to three decades it has become clear that tumor growth is dependent upon the growth of new vessels [3].