A87: Proliferative activity, lymphatic and blood vessel density in different clinical stages of melanoma

Abstract

Cutaneous melanoma is one of the most aggressive human neoplasms that can quickly metastasize to regional lymph nodes. Currently, prognosis is determined by measuring tumor thickness but more reliable markers for metastatic spread are urgently needed. It is well known that tumors require a microvasculature development in order to grow and metastasize. Angiogenesis and lymphangiogenesis play an important role not only in the tumor growth, but also in the tumor metastasis. As malignancy is a disorder of cellular growth control, the assessment of cell proliferation rates in tumors has intuitive appeal as a prognostic marker. One such biomarker is Ki-67, a cell cycle dependent protein. Recent reports related to its role as a prognostic factor have been contradictory. The purpose of this study was to investigate lymphangiogenesis, angiogenesis and tumor tissue proliferative activity depending on the clinical stages of melanoma. The objects of the study were the samples of tumor tissue obtained during surgical treatment of cutaneous malignant melanoma. To analyze tumor angiogenesis, lymphangiogenesis and proliferation, we performed immunostains of the primary melanomas for the vascular marker CD34, for the lymphatic-specific markers LYVE-1, D2 -40 (Podoplanin) and marker of proliferation – Ki-67. Samples of tumor tissue from 40 patients with IA, IB, IIA, IIB, IIIC melanoma stages were fixed in 10% neutral formalin, processed by standard histological techniques and embedded in paraffin. All steps of the immunohistochemical reaction were performed by using BENCHMARK/XT slide stainer (Ventana). Determination of blood vessel volume density revealed its growth an average of 2 times in peritumoral areas. Similar data were obtained about the location lymphatic vessels. Greater content peritumoral blood and lymphatic vessels, then intratumoral could be detected in all stages of melanoma. In addition more significantly greater volume density both intratumoral and peritumoral blood vessels, than lymphatic vessels was found. A greater degree expression of endothelium lymphatic vessels markers Podoplanin, compared with the LYVE-1 was shown. It was noted an increasing volume density of the peritumoral blood and lymphatic vessels in primary tumors with expansion clinical stage melanoma. Three levels of proliferative activity of tumor tissue were determined (low, an average degree and high Ki-67 expression). Results of the analysis have shown, that the high proliferative activity corresponded to significant content of blood and lymphatic vessels. High level of these markers was observed in patients with regional lymph nodes metastases. In recent years there have been appeared publications suggesting that lymphatic vessel density (particularly in a peritumoral location) and lymphatic vessel invasion are predictors of sentinel node metastasis and poorer survival. It was noted, that “larger, carefully conducted and well-reported studies that confirm these preliminary findings are required before it would be appropriate to recommend the routine application of costly and time-consuming immunohistochemistry for lymphatic markers in the routine clinical assessment of primary cutaneous melanomas”. In our opinion, one must consider not only the lymphatic vessels density, but also blood vessels, and the tumor tissue proliferative activity. Conclusion This study has shown that the complex markers of lymphangiogenesis (Podoplanin), angiogenesis (CD34) and proliferation (Ki-67) may be predictors of high risk early melanoma metastasis.