Quantitative molecular grading of bladder tumours: A tool for objective assessment of the biological potential of urothelial neoplasias

Abstract

The present study aimed to assess whether patients with bladder urothelial tumours can be more objectively stratified into low- and high-risk groups for recurrence and progression using a 2-tired molecular grading scheme, than by subjective histopathological grading alone. Biopsy material from 45 consecutive patients with urothelial bladder neoplasias (2 papillary urothelial neoplasm of low malignant potentials, 18 pTa, 1 pTis, 19 pT1 and 5 pT2) was analysed for immunohistochemical Ki-67 and p53 expression. Labelling indices were assessed by automated cellular image analysis. UroVysion FISH test results were evaluated by automated signal counting, and DNA ploidy of single nuclei preparations were measured by image cytometry. Sixty-nine percent of cases showed >10% Ki-67 LI, 64% had >10% p53 LI, 53% revealed DNA aneuploidy and 56% expressed a high-risk FISH pattern. Based on a combination of single molecular markers, 75% of neoplasias were classified as high molecular grade. Tumour stage and histopathological grade were significantly associated with FISH pattern, DNA ploidy and MIB1 LI. Stage was also related with molecular grade. Clinical outcome showed a significant correlation with MIB1 LI and molecular grade. P53 had neither diagnostic nor prognostic relevance, nor was there any correlation between histological and molecular grade. Our preliminary data strongly suggest that the combination of quantitative biomarkers provides superior and objective prognostic tools in bladder urothelial neoplasias compared to classic clinicopathological features and indices.