Pathology of Tumor Angiogenesis

Abstract

Angiogenesis, commonly used to describe the process of vessel growth, defines the sprouting process from preexisting vessel and plays a pivotal role for vital beneficial processes, diseases, and harmful neoplastic lesions. Physiological angiogenesis is a temporary and locally limited process appearing in reproduction, development, and wound repair, depending on a balanced equilibrium of pro- and anti-angiogenetic directing angiogenesis.

During tumor genesis, epithelial cells have to pass a sequence, starting with epithelial dysplasia, followed by carcinoma in situ, and finally resulting in the invasive cancer. Invasive cancer has the capacity to infiltrate the surrounding tissue, to sprout to distant sides, and to form metastases. Hereby, the invasive process is accompanied with a significant cell proliferation and increasing tumor size. Without additional oxygen and nutrient support, tumors will arrest/decline their growth or even die. Tumor cells exploit the above-described physiological processes by hijacking local vessels and modifying the surrounding microenvironment to ensure oxygen and nutrition supply. The following chapter will present an overview into the pathology of angiogenesis focusing on embryological process of vessel development, namely, vascular genesis and angiogenesis, vessel formation modes, effects of malignant tumors and precursor lesions onto angiogenesis, and histological architecture in malignant tumors.