Biological Characterisation of Superficial Bladder Cancer by Bivariate Cytokeratin 7/DNA Analysis, Flow Cytometric Assessment of MIB-1, and an Immunohistochemical Study

Abstract

A total of 238 cases of bladder carcinoma stages Ta, Tis, T1 were submitted prospectively to multiparameter flow cytometry and immunohistochemical study in order to determine the biological aggressiveness of the tumour. DNA index (DI), S-phase fraction (SPF) obtained by bivariate cytokeratin 7=DNA analyses, and the immunohistochemical evaluation of p53 and MIB-1 were studied in relation to the traditional prognostic factors in bladder cancer (stage and grade). The variance analysis results showed that DNA aneuploidy was significantly associated with high stage (p= 0:0001), high grade (p= 0:0001), high SPF value ≥5.5% (p= 0:0001), MIB-1 positivity ≥31% (p= 0:0001) and high expression of p53 (staining involving >50% of cells,p= 0:0001). Even if there was no statistical significance the hypotetraploid class (1.70<DI<1.89) showed poor prognostic biomarkers more frequently than the other aneuploid classes. Out of 238 cases, 101 were also submitted to flow cytometric measurement ofMIB-1 (fMIB-1) to study the correlation between cell proliferation and DNA content. Data obtained from fresh, 3 : 1 methanol=acetone fixed samples were compared with values obtained from both cell cycle analysis methods and routine application of the MIB-1 immunostaining in histological sections. fMIB-1 values were positively correlated with SPF values (r= 0:801,p< 0:01) and S+G2M fraction (percentage of cells in S and in G2M phases) (r= 0:763,p< 0:01) but no correlation with paraffin sections was found. A fMIB-1 value >7% was strongly associated with aneuploidy (p= 0:0001). The determination of DNA content coupled with the study of the epithelial (cytokeratin 7) and proliferative (MIB-1) markers could be useful in providing important information on the biological behaviour of superficial bladder tumours.