Expression and prognostic relevance of vascular endothelial growth factor (VEGF) and its receptor (FLT-1 in nephroblastoma

Aims: To investigate the prognostic relevance of vascular endothelial growth factor (VEGF) and its receptor Flt-1 in nephroblastoma and whether tumour microvessel density (MVD) immunoreactivity, determined by the CD31 antigen, is related to the expression of VEGF and Flt-1. Methods: The expression of VEGF and FIt-1 and MVD were investigated by means of immunohistochemical analysis in 62 Wilms's tumours. Patients were treated preoperatively with chemotherapy and had a mean follow up of 5.7 years. Results: In general, VEGF and FIt-1 were expressed in normal kidney parenchyma and to a variable extent in the three main components of Wilms's turnout, namely: the blastemal, epithelial, and stromal cells. In tumour tissue, 52% and 47% of blastemal cells were positive for VEGF and FIt-1, respectively. A non-significant correlation was found between the expression of VEGF and Flt-1 in blastemal and epithelial cells and the clinicopathological stage. MVD was significantly higher in VEGF and FIt-1 positive tumours than in VEGF and FIt-1 negative tumours. Univariate analysis showed that the expression of VEGF and Flt-1 in blastemal cells was indicative of clinical progression and turnout specific survival. In addition, MVD expression was indicative of clinical progression. Epithelial staining was of no prognostic value. In a multivariate analysis, VEGF protein expression by blastemal cells was an independent prognostic marker for clinical progression. Conclusions: These results indicate that VEGF and FIt-1 protein expression are closely related to MVD and seem to be an important predictor for poor prognosis in treated patients with Wilms's tumour. Therefore, the expression of these molecules in primary Wilms's turnout may be useful in identifying those patients at high risk of tumour recurrence and in guiding antiangiogenic treatment.