Determination of angiogenesis in human neoplasms: current prognostic and therapeutic implications

The growth of solid tumours beyond a certain mass is strictly dependent on the formation of a vascular bed from a pre-existing host vasculature. This process has been termed OangiogenesisO and its importance in the process of tumour growth and metastasis has recently gained wide acceptance. Studies have been reported in several kinds of human cancers in which the number of microvessels in the most intense areas of neo-vascularisation (Ohot spotsO) have been shown to be strictly related to the development and progression of the tumour. In the majority of these studies highly vascularised tumours showed a poor prognosis and the influence of tumour angiogenesis proved to be independent of conventional prognostic indicators. The evaluation of tumour angiogenesis by quantitative pathology may represent an important prognostic indicator in human cancers and will be increasingly important in the investigation of new therapies directed to inhibiting angiogenesis or targeting tumour vasculature. This review will briefly summarise the current knowledge on the prognostic impact of tumour angiogenesis in human cancers with a final reference to angiogenesis inhibitors which are currently used in phase I/II and III clinical trials.