Expression of VEGF and microvessel density in patients with multiple myeloma: clinical and prognostic significance

Abstract

The conflicting data are reported on the clinical significance of VEGF deregulation and intensity of angiogenesis in multiple myeloma. The aim of this study was to evaluate the incidence and prognostic significance of VEGF expression and microvessel density (MVD) in multiple myeloma, as well as the relationship of their expression with selected clinical data, histological features, and proliferative activity of myeloma cells. We analyzed bone marrow biopsy specimens obtained from 59 patients with newly diagnosed multiple myeloma. Expression of VEGF and MVD was analyzed using standard immunohistochemical method (antibodies against VEGF and CD34, respectively) on B5-fixed and routinely processed paraffin-embedded bone marrow specimens. MVD was estimated by counting the number of microvessels in three "hot spots" at 400x magnification. VEGF immunoreactivity was estimated on the basis of intensity and percentage of positive plasma cells. VEGF was expressed in 47/59 (79.7%) specimens. There was no significant correlation between VEGF overexpression and age, clinical stage, the extent of osteolytic lesions, type of monoclonal protein, hemoglobin concentration, platelet count, serum concentration of creatinine, calcium, and albumins, the extent of bone marrow infiltration, histological grade, and proliferative activity index (measured with Ki-67 immunoreactivity). No significant difference was observed regarding the overall survival between VEGF-positive and VEGF-negative patients (29 vs. 34 months, P = 0.8). Median MVD was 15, ranging from 1 to 89 microvessels per three "hot spots". There was significant correlation between MVD and histological grade, the extent of bone marrow infiltration, and proliferative activity. Significant difference was observed regarding the overall survival between patients with low MVD (<15) and patients with high MVD (> or = 15) (46 vs. 22 months, P = 0.009; univariate analysis). The results of this study did not reveal clinical significance of VEGF overexpression in multiple myeloma. On the contrary, the extent of bone marrow angiogenesis is an indicator of biological potency of malignant clone and a predictor of poor survival in newly diagnosed myeloma.