The Role of Microvasculature in Metastasis Formation

The development of a microvascular network within tumours, also termed tumour angiogenesis, is an essential process for the development and outgrowth of cancer metastases. Metastases develop through a series of interlinked steps, each of which is essential for the establishment and progression of a metastatic lesion. After an initial phase of extensive tumour cell proliferation in the primary lesion and creation of an extensive vascularization network from pre-existing vessels (vessel cooption), tumour cells may elicit the ability to invade the extracellular matrix for entering the bloodstream, lymphatic channels, or both. However, similarly to the primary lesion, metastatic lesions must establish a sufficient microvascular network at an organ site (which in addition displays a different microenvironment compared to the primary lesion), in order to facilitate their outgrowth. This chapter provides a comprehensive overview on factors regulating the complex process of tumour angiogenesis and metastases formation, with respect to various solid malignancies.