Tumor angiogenesis: A pathologist's point of view

The study of tumor angiogenesis is currently one of the leading themes in oncology. This is justified by the importance of tumor angiogenesis in the natural history of cancer, the possible applications of angiogenesis markers as prognostic factors and the emergence of innovative anti-tumor treatments based on anti-angiogenic strategies. Pathologists have largely contributed to the study of tumor angiogenesis ^1,2. They had given the first detailed descriptions of the process and their observations have been essential to the understanding of the role of tumor angiogenesis in the natural history of cancer. More recently, pathologists had a leading role in the evaluation of the possible prognostic applications of angiogenesis markers and some of them have participated to the analysis of the in vivo effects of anti-angiogenic therapeutic strategies. However, not all the lessons which may be drawn from the histopathological analysis of the tumors and of their relations with the tissue from which they originate have yet been taken into account. Some of these may be of relevance for a better understanding of the mechanisms of tumor angiogenesis and a more accurate interpretation of the relationships between tumor cells, neovessels and their microenvironment. The aims of this review are, after a brief summary of the current concepts about tumor angiogenesis, to discuss the following points : (a) the contribution of tumor histopathology to the understanding of the mechanisms of tumor angiogenesis, (b) the critical analysis of the morphological techniques allowing the evaluation of angiogenesis markers as prognostic indicators, (c) the possible role of morphological techniques in the evaluation of anti-angiogenic strategies.