ASSESSMENT OF PROLIFERATIVE ACTIVITY IN WILMS-TUMOR

The proliferative activity in 26 cases of Wilms' tumour was studied by enumeration of silver-staining nucleolar organizer regions (AgNORs) a nd 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 fo llow-up 95 months) at the time of the study. The prognostic significan ce of PCNA and AgNOR for Wilms' tumour was evaluated by dividing the t umours into groups exhibiting low (PCNA less than or equal to 40 or Ag NOR less than or equal to 4) or high (PCNA > 40 or AgNOR > 4) prolifer ative activity. There was a significant difference in the survival of the two groups for tumours treated with preoperative chemotherapy (PCN A, P = 0.049; AgNOR, P = 0.02), while no significant difference was ob served from tumours resected prior to the administration of chemothera py. The results of this study suggest that assessment of proliferation activity in postchemotherapy Wilms' tumours may be a useful indicator of prognosis.