Standardized AgNOR analysis of the invasive tumour front in oral squamous cell carcinomas

In the last decade, silver staining of nucleolar organizer region-associated proteins (AgNORs) has been widely used in tumour pathology both for diagnostic and for prognostic purposes. However, a reliable and reproducible assessment of these proteins on routinely processed archival tissues has only become possible since the recent introduction of standardized staining method and computer-aided morphometric analysis. In the present study, the AgNOR content at the invasive front of 80 squamous cell carcinomas of the floor of the mouth/tongue was investigated using this novel approach, with regard to prognosis and a variety of clinico-pathological parameters. All standardized AgNOR parameters [mean of AgNOR number, mean of AgNOR area, coefficients of variation (CV) of both AgNOR number and area] were statistically significantly associated with the clinical course. The strongest correlation was found for the AgNOR-area univariate analysis (P = 0.006). In multivariate analysis, the mean of AgNOR number could independently predict both overall (P = 0.01) and disease-free survival (P = 0.001). It is concluded that standardized staining and computer-aided analysis of AgNORs are prerequisites for an objective and reproducible AgNOR assessment, which has potential as a supplementary diagnostic and prognostic tool in oral cancer.