PC-10 antibody to proliferating cell nuclear antigen (PCNA) is not related to prognosis in human breast carcinoma.

The PC-10 monoclonal antibody to PCNA was employed to analyze proliferative grade in conventionally-formalin fixed, paraffin-embedded tumour samples of 162 patients with primary breast carcinoma. To perform the immunocytochemical method, sections were not heated, were de-waxed using alcohol, and then immersed in a phosphate-buffered saline solution and in methanol with 0.5% hydrogen peroxide to block endogenous peroxidase activity. Immunostaining was performed by a streptavidin-biotin peroxidase substrate. A semiquantitative scoring system was used to evaluate the fraction of nuclei that were PCNA-positive. The score ranged from 0% to 75% with a median value of 25%, mean of 27.8 +/- 1.5. PCNA staining was significantly associated with oestrogen receptor-negativity (p = 0.011) and correlated, but not at a statistically significant level, with tumour size (p = 0.08). No significant association was observed between PCNA and node status, grading, DNA ploidy, progesterone receptor or menopausal status. Prognostic indices such as number of positive lymph nodes and DNA ploidy were significantly associated with relapse-free survival (RFS) and overall survival (OS). No significant correlation between PCNA nuclear immunostaining and RFS or OS was observed after a median follow-up of 4 years. Our results indicate that analysis of PCNA alone does not seem to be a useful marker in identifying patients at different prognosis in human breast cancer.