Nucleolar organizer regions in carcinomas of the oropharynx and hypopharynx.

It is supposed that the nucleolar organizer regions (NORs), genes on which ribosomal RNA is coded, may contain information on the structure of the nucleolus and on nucleolar activity which permits discrimination between normal and neoplastic cells and their proliferation activity. In the present study, the histological sections of 144 patients with carcinomas of the oropharynx and hypopharynx were studied in a retrospective approach to determine the absolute NOR counts per 100 nuclei and investigate their influence on the prognosis and extent of lymphogenic formation of metastases. An absolute NOR count of 681 per 100 nuclei was found to give reliable discrimination between stage N0 or N1 carcinomas and stage N2 or N3 disease.