Assessment of proliferative activity in Wilms' tumour

The proliferative activity in 26 cases of Wilms' tumour was studied by enumeration of silver-staining nucleolar organizer regions (AgNORs) and proliferating cell nuclear antigen (PCNA) staining of the blastemal, epithelial and stromal components of the tumours. The PCNA and AgNOR scores derived from the blastemal (PCNA range 18.9-81.4%, AgNOR range 2.11-4.95) and epithelial (PCNA range 24.1-74.2%, AgNOR range 2.47-4.41) components of the tumours were significantly higher than those of the stromal component (PCNA range 3.4-64.7%, AgNOR range 2.20-4.26). Ten of the patients had died with recurrent or metastatic tumour (mean survival 29 months) while the remaining 16 were disease free (mean follow-up 95 months) at the time of the study. The prognostic significance of PCNA and AgNOR for Wilms' tumour was evaluated by dividing the tumours into groups exhibiting low (PCNA < or = 40 or AgNOR < or = 4) or high (PCNA > 40 or AgNOR > 4) proliferative activity. There was a significant difference in the survival of the two groups for tumours treated with preoperative chemotherapy (PCNA, P = 0.049; AgNOR, P = 0.02), while no significant difference was observed from tumours resected prior to the administration of chemotherapy. The results of this study suggest that assessment of proliferation activity in postchemotherapy Wilm's tumours may be a useful indicator of prognosis.