Prognostic value of p53 expression in Wilms' tumor in children.

Background: The aim of this report was to evaluate the prognostic value and clinical correlations of p53 expression in children with Wilms' tumor.

Material And Methods: The study comprised 61 children aged from 2 days to 13 years (median 39 months), diagnosed and treated according to SIOP and PPGGL criteria in three centers co-operating with the PPGGL. The studies were conducted on tumor tissue removed during surgery, fixed in formalin and embedded in paraffin blocks. Then 4-micron sections were evaluated by immunohistochemistry, using the peroxidase method to determine the expression of p53 in Wilms' tumor cells by means of primary monoclonal antibody NCL-p53 from Novocastra.

Results: The percentage of immunopositive cells in particular fragments of the tumor ranged from 0% to 70% (mean 20.4%, median 16.0%). The mean and median values enabled the children to be divided into two groups: Group A, where the percentage of cells staining with anti-p53 antibody was >20% (23 cases), and Group B, where this percentage did not exceed 20%. The expression of p53 was then evaluated in various stages of advancement and various histological types, depending on the course of the disease. In Group A, tumors at higher stages of advancement stages were more frequent (p<0.05), and showed a higher degree of malignancy (p<0.06; EFS=56.53%). In Group B, lower stages of advancement were more frequent (p<0.05), the degree of malignancy was lower, and the EFS was 81.58%. A discrimination test, however, showed that the determination of p53 expression in Wilms' tumor cells has moderate sensitivity (58.825%), positive prediction (43.47%), and relatively high specificity (70.45%) and negative prediction (81.57%), which means that low indexes of p53 expression have higher prognostic value.

Conclusions: The index of p53 expression is not an independent prognostic factor in Wilms' tumor in children, but this determination may be helpful in identifying high-risk and low-risk patients.