Prognostic significance of nucleolar organizing regions (NORs) in carcinomas of the sigmoid colon and rectum.

The prognostic significance of silver-binding nucleolar organizing regions (AgNORs) has been evaluated in tissue sections of biopsies taken from 70 primary adenocarcinomas of the colon sigmoid (n = 25) and rectum (n = 45) prior to their curative resection. A significant correlation between five-year survival rate and the mean AgNOR number per tumour cell (p less than 0.001) and the mean size of silver stained dots (p less than 0.05) was found according to the univariate Kaplan-Meier survival analysis. There was no significant relationship between AgNOR content and grade of malignancy, pT categories or pN categories. Multivariate survival analysis of covariates (Cox regression model) revealed a set of five variables that significantly influenced the patients' outcome: pN categories, AgNOR content, pT categories, maximum grade of malignancy and number of inflammatory cells. From the clinical and pathological parameters studied, pN and pT categories as well as the mean AgNOR number were the most important variables predicting death from colorectal carcinoma. Since the analysis of AgNORs can be performed on routinely processed paraffin-embedded tissue, this method may be of potential use in pretherapeutic assessment of the biologic aggressiveness of the disease.