Cyclin A expression in bladder cancer: Correlation with Ki67 index

Introduction: Cell proliferation follows an orderly progression regulated by proteins called cyclins. These include the mitotic cyclins A and B associated with G2/M phase transition and the C, D and E cyclins which are active in G l. The aim of this study was to investigate the expression of cyclin A in TCC of the bladder and to relate this to the expression of Ki67. an established marker of tumour growth fraction which is expressed in all phases of the cell cycle except GO. Materials and methods: Tumours (139) were obtained endoscopically from 54 patients (44 men and 10 women, mean age 72 years; Ta in 83. T1 in 35, T2-T4 in 21; Gl in 57, G2 in 66 and G3 in 16). The expression of cyclin A and Ki67 were assessed using standard immunohistochemistry with scores based on the percentage of positive nuclei. Results: Cyclin A expression was detected in all tumours (median score 14.4%, range 1-59). There was a significantly higher cyclin A expression in G2/G3 tumours (median score 17.5%) than in G1 tumours (median score 11.2%, P< 0.05). There was no correlation between cyclin A expression and tumour stage. The median Ki67 score was 18.6% (range 0-82) and was similarly higher in G2/G3 tumours (P < 0.002). Cyclin A expression correlated with Ki67 expression (P< 0.001). Conclusion: The expression of cyclin A correlates with highgrade tumours and Ki67 expression. The clinical significance of this remains to be determined. © 1998 British Journal of Urology.