Nucleolar organiser regions (NORs) in bladder cancer; relation to histological grade, clinical stage and prognosis.

Nucleolar organiser regions (NORs), which are related to regulation of protein synthesis and cell proliferation, were estimated subjectively in 89 bladder cancer patients by means of silver staining technique on archival paraffin sections. The number of Ag-NORs was correlated to histological grade (WHO), clinical stage (UICC) and clinical behaviour of tumours during a mean follow-up period of 14 years. Total number of Ag-NORs and the number of dispersed Ag-NORs were significantly related to histological grading and clinical stage. In particular, grade III tumours (p = 0.0002) as well as T3-T4 tumours (p = 0.0591) showed high numbers of Ag-NORs in comparison to superficial low grade tumours. Non-papillary tumours showed higher Ag-NOR counts as cell (p = 0.0012). Ag-NOR count was also related to lymph node involvement (p = 0.0418) and metastasis (p = 0.0713) with borderline significance. Patients dying of bladder cancer showed higher Ag-NOR counts and in survival analysis the number of dispersed Ag-NORs was related significantly to survival (p = 0.0201). Our conclusion is that despite significant differences in Ag-NOR counts they are of limited use for diagnosis and prediction of any single case in bladder cancer. The results, however, clearly indicate the need for further studies before the clinical importance of the Ag-NOR staining method can be fully appreciated in bladder cancer.