Polyclonal Ki-67 expression in transitional cell carcinoma of the bladder

ABSTRACT

Current methods of predicting prognosis in transitional cell carcinoma [TCC] of the bladder fail to provide consistently reliable information about future tumor behavior. The polyclonal antibody Ki-67 recognizes a nuclear antigen exclusively present in cells in the cell cycle. The Ki-67 reactivity has been shown to correlate with conventional prognostic indicators in several tumors.We studied the proliferative activity of 40 cases of transitional cell carcinomas of the bladder using polyclonal Ki-67 and determined the proportion of cells undergoing active division. A significant correlation was observed between cells with activated DNA [Ki-67], histological grading and staging [P< 0.0001]. The differences of mean Ki-67 index in the grade Ila versus lib [using Pauwell classification] was also significant [P<0.044]. Those cases which were limited to epithelial layer [stage Ta] show lower Ki-67 positivity than those infiltrating the lamina properia or deeper layers [stage Tl, T2, T3 and T4][P< 0.05]. The differences between stage Tl versus T2 and T3 versus T4 were not statistically significant [P>0.05]. The tumors with lymphatic and vascular invasion showed greater Ki-67 positivity than non-invasive tumors [P<0.01] These results suggest that the immunohistochemical assessment of the proliferative activity of transitional tumors of the bladder, using polyclonal antibody Ki-67 correlates with higher tumor stage and grade. Ki-67 staining provides an easy method of determining tumor cell turnover that might provides additional prognostic information. The results also indicate that the number of Ki-67 positive cells in grade II tumors may be useful aid in separating grade II TCC with favorable prognosis [Ila] from those with a poor clinical outcome [lIb]