Prognostic significance of nucleolar organizer regions in adenoid cystic carcinomas of the head and neck.

Abstract

To determine the prognostic use of nucleolar organizing region (AgNOR) counts and clinical and histopathological features in adenoid cystic carcinoma. Argyrophilic staining was applied to ordinary formalin-fixed, paraffin-embedded specimens and evaluated to obtain the mean number of AgNORs and the percentage of nuclei with more than 1 (pAgNOR > 1), more than 2, more than 3, and more than 4 AgNORs. Using the log rank test, the mean AgNOR count showed no correlation with the disease-free period. All pAgNOR parameters exceeding the respective overall mean had poorer prognosis when compared with those below the mean (P = .02). The pAgNOR > 1 appeared as the best discriminator, singling out all treatment failures (P < or = .001). This parameter also showed a high degree of intraobserver and interobserver reproducibility. Stage of the disease, violated resection margins, and presence of the histopathological solid subtype were markers of an unfavorable prognosis. Multivariate analysis by the Cox model showed that pAgNOR > 1 (P < or = .001) and tumor stage (P = .03) were the only statistically significant parameters. Estimation of pAgNOR > 1 is easy, quick, and highly reproducible. It may become a useful prognostic parameter in adenoid cystic carcinoma, but larger studies should be performed to confirm the reliability of this method.