Immunohistochemical analysis of proliferating cell nuclear antigen (PCNA) in infiltrating ductal carcinomas:...

PC10, a monoclonal antibody directed against proliferating cell nuclear antigen (PCNA), was used to study the percentage of cells and range of immunopositivity in formalin-fixed paraffin-embedded tissues of 39 infiltrating ductal carcinomas. The percentage of immunostained nuclei was compared to the results of seven clinical and pathologic variables and also to each of the three components of tumor grade. The range of percent positivity was 3% to 85% (median: 36%). There was no statistically significant correlation between percent PCNA positivity and patient age, axillary lymph node status, estrogen or progesterone receptor levels, ploidy, tubule formation, or nuclear pleomorphism. Significant correlations were seen between percent PCNA positivity and tumor size (p = 0.03), grade (p = 0.0005), and mitotic rate (p = 0.0001). These data suggest that, in studies examining PCNA immunoreactivity as a potentially important prognostic parameter for patients with infiltrating ductal carcinoma, tumor size and either grade or mitotic count must be considered as variables in the multivariate statistical analysis.