Monoclonal antibody Ki-67 in the study of the proliferative activity of bladder carcinoma

We studied the proliferative activity of bladder carcinoma using monoclonal antibody Ki-67, which is able to stain a nuclear antigen exclusively present in cells in the cell cycle, that is with activated deoxyribonucleic acid (DNA). We used this immunohistochemical technique on neoplastic tissue removed by transurethral resection from 101 patients. A significant correlation was observed (p less than 0.003) between cells with activated DNA and histological grading, even though within the context of each grade we observed tumors with a different proliferation index. Furthermore, we studied the location of the activated cells in the context of the tumor. In invasive tumors (stages T1 to T4) cells with activated DNA were always present at the base of implant of the tumor and in the neoplastic tissue that infiltrates the bladder wall. In regard to noninvasive tumors (stage Ta), in 57% of the cases most cells with activated DNA were present in the vegetative portion of the tumor and there were no recurrences at followup, while in 43% of the cases such cells were present also or especially at the base of implant of the tumor, near the lamina propria. In the latter patients we observed a 94% recurrence rate. These results suggest that the immunohistochemical assessment of the proliferative activity of transitional tumors of the bladder, using monoclonal antibody Ki-67, and the evaluation of the location of stained neoplastic cells provide a more reliable estimate of biological aggressiveness than that obtained with histopathological patterns alone.