Prognostic significance of vascular endothelial growth factor expression in clear cell renal cell carcinoma

The purpose of this investigation was to analyze and correlate the immunohistochemical pattern of vascular endothelial growth factor (VEGF) expression with the average of microvessel density (MVD) and other clinicopathologic parameters in clear cell renal cell carcinoma (CCRCC) in order to determine its prognostic significance. Surgical specimens of 93 CCRCC were immunohistochemically analyzed for VEGF expression, MVD with anti-CD31, and Ki 67 proliferative index. VEGF expression was recorded as the percentage of positive tumor cells (<75% and >75%) and as diffuse or perimembranous VEGF expression according to cytoplasmic distribution. Sixty-three (68%) RCC had <75% and 30 had (32%) >75% of VEGF expression. A diffuse cytoplasmic pattern of VEGF expression was found in 61(66%) RCC and a perimembranous one in 32 (34%) RCC. Statistical analysis showed that tumors with >75% of VEGF expression were characterized by lower MVD value (p=0.034), higher nuclear grade (p=0.018), and higher Ki 67 proliferation index (p=0.023). Moreover, a higher nuclear grade of tumor cells was characterized by diffuse cytoplasmic VEGF distribution (p=0.005). This tumor model did not confirm the postulated simple relationship between VEGF overexpression and angiogenesis through high microvessel count. However, the study results indicated that overexpression of VEGF was a worse histologic prognostic parameter in CCRCC.