PCNA/cyclin expression in transitional cell carcinomas of the human bladder: its correlation with Ki-67 and epidermal growth factor receptor immunostainings.

Cell kinetic data are an important adjunct to histologically based tumor classifications and provide reliable information about future tumor behaviour. The growth fraction of 62 transitional cell carcinomas was assessed using Ki-67 and PCNA (Proliferating cell nuclear antigen/cyclin) immunostainings. Ki-67 recognises an unknown nuclear antigen expressed in dividing cells and requires the use of frozen sections. PCNA, a non histone nuclear protein, identifies proliferating cells within fixed, embedded tissue sections. The percentage of labeled cells was expressed as the labeling index (LI). The median LI in normal urothelium and transitional cell carcinoma were 0.5% and 8%, respectively for Ki-67, and 1.5% and 12% for PCNA. A general agreement between indices of cell proliferation and histological grade and stage was demonstrated. Although some discrepancies were observed, there was a strong correlation between Ki-67 and PCNA Lis (r = 0.8308, P < 0.01). In addition, tumor EGFR positive had PCNA values greater than those found in cancer EGFR negative (P = 0.01). These findings suggest that immunohistochemical nuclear labeling with anti-PCNA on routinely processed tissue is a simple technique for the assessment of transitional cell carcinomas.