Аngiogenesis in Uveal Melanoma

Abstract

Uveal melanoma (UM) is less than 0.5 % in the spectrum of human tumors, and less than 5 % among all types of melanoma, therefore, it is considered to be rare. At the same time, UM is recognized as the most common intraocular malignant neoplasm. Its share among all intraocular tumors is 60 %. Radical local treatments are considered effective, but the frequency of distant metastases is unacceptably high, and the life expectancy of patients with metastatic stage of the disease is short and on average is 4–5 months. Survival rates have remained stable for the past 40 years, reflecting the lack of current effective system strategies. The tumor metastasizes in a haematogenic way, so it is not surprising that angiogenesis is constantly in the focus of scientific developments. The importance of studying angiogenesis in UM is due to the ability to predict based on the quantitative indicators of vessels inside the tumor and to search for potential targets of antiangiogenic therapy in the future. The authors used two methods of studying angiogenesis in UM: morphological with quantitative vascular counting and immunohystochemical method (IHC) with markers of endothelial cells CD34 and CD31, VIII factor, VEGF molecules, bFGF, thrombospondin and others. IHC-staining of vessels in UM allowed to visualize vessels that were not visible due to intense pigmentation of tumors or compression of vessels by tumor cells. Comparison of data obtained by the two methods demonstrated the advantages of IHS analysis over classical morphological methods. It was found that UM, as a malignant solid tumor, differs high averages of vessels per unit area. The highest rates are recorded in epitheloid melanoma, which is associated with a higher rate of growth, and more frequent metastasis, compared to similar rates in revere cell melanoma. The number of vessels per unit area in the viewing area in UM decreases with age, which explained the development of metastases in more distant after enucleation time in elderly patients. Differences in vascular density in tumors of different localization were revealed and described: they were the maximum in pre-equatorial tumors, and minimal — in iris tumors.