Proliferating cell nuclear antigen expression in renal cell carcinoma. Prognostic implications.

The proliferating cell nuclear antigen (PCNA) is a nuclear protein associated with cells in active cell cycle. The expression of PCNA was evaluated immunohistochemically in 3-6 samples from 68 renal cell carcinomas. A total of 279 tumour samples were analysed using the monoclonal antibody PC-10, and the percentage of positively stained cell nuclei (PCNA-index) was determined. The tumour PCNA-index varied between 0.9-17.5%, with a mean value of 4.9%, significantly different from normal kidney cortex samples (p < 0.001). A significant difference in PCNA-index was found between the different tumour grades, whereas no significant difference was found between clinical stages. Concerning DNA ploidy, aneuploid tumours had a significantly higher PCNA-index compared with diploid tumours (p = 0.002). There was a significant survival advantage for patients with low tumour PCNA-indices (< 3.5%) compared with those with high indices (> 3.5%, p = 0.019), a difference also found for patients with non-metastatic disease (p = 0.012). Our data shows that PCNA expression can be analysed and that it may constitute an additional prognostic parameter for patients with renal cell carcinoma.