P53 PROTEIN EXPRESSION IN NEPHROBLASTOMAS - A PREDICTOR OF POOR-PROGNOSIS

Alteration of the tumour-suppressor gene p53 is the commonest genetic change encountered in human malignant tumours. A study was undertaken to ascertain the prognostic value of p53 immunoexpression in nephrobla stomas. A series of 93 consecutive cases was analysed. Archival formal in-fixed, paraffin wax-embedded tissue sections were stained with mono clonal anti-p53 antibody (DO-7, Dako) using a peroxidase-labelled stre ptavidin biotin kit. Five of seven tumours (71.4%) with unfavourable h istology, but only 3 of 86 favourable histology tumours, showed 'high' p53 immunoexpression (P < 0.001). p53 expression in unfavourable hist ology tumours was present in both anaplastic and non-anaplastic compon ents. Moreover, there was uniform staining of blastema, epithelium and stroma in unfavourable histology tumours. No statistical difference i n p53 expression was found between patients who had received and those who had not received preoperative chemotherapy (P = 0.678). Similarly , no statistical difference was found in the groups of patients who we re disease free, who had residual/recurrent disease or who had died (P = 0.238). The mean survival period for patients with tumours that had 'low' and 'high' expressions was 24.8 months and 12.6 months respecti vely (P = 0.0003). In conclusion, p53 immunoexpression in nephroblasto mas was found to be an important determinant of poor prognosis as it i dentifies those patients with a shorter survival period and also those with unfavourable histology tumours. It may also be of practical valu e to the practising pathologist by identifying those tumours that requ ire careful assessment for the presence of anaplasia.