AgNOR Count in Resting Cells (Resting NOR) Is a New Prognostic Marker in Invasive Bladder Tumor
PURPOSE It has been shown in many carcinomas that the proliferation rate and number of argyrophilic nucleolar organizer regions (AgNOR) are associated with tumor aggressiveness. However, in bladder tumor the significance of the correlation between the number of AgNOR and tumor behavior remains controversial. Therefore, it would be helpful if a new technique could be developed that would allow for more accurate AgNOR counting in association with tumor behavior. We established the simultaneous staining technique of AgNOR with Ki-67 labeling to reveal the significance of AgNOR count in superficial bladder tumor. MATERIALS AND METHODS A total of 50 paraffin sections of superficial bladder tumor were stained with AgNOR and Ki-67 (MIB-1). The numbers of AgNORs in proliferating (MIB-1 positive) or resting (MIB-1 negative) cells were counted from a total of 100 nuclei. Correlations between MIB-1 associated AgNOR count and clinicopathological parameters were statistically analyzed. RESULTS The AgNOR count in proliferating cells was significantly higher than that in resting cells (p<0.01), and the count significantly increased with tumor grade (p<0.01). Based on recurrence-free survival analyses the local recurrence rate was significantly higher in patients with high proliferating cell NOR but not for those with resting or whole cells. However, no AgNOR score helped to select patients at high risk for disease progression. CONCLUSIONS Proliferating cell NOR had a predictive value for local recurrence in patients with superficial bladder tumor.