Evaluation of argyrophilic nucleolar organizer regions (AgNORs) in differentiated thyroid carcinoma as an indicator for disease recurrence.

Differentiated thyroid carcinoma (DTC) is one of the least aggressive cancers of the human malignancies, however, recurrent disease is occasionally found and is difficult to determine the risk for recurrence only by clinicopathological features. In the present study, we investigated argyrophilic nucleolar organizer regions (AgNORs) score, a well-known indicator for proliferative potential of the cancer cells, in 89 cases of DTC. In tumors with capsular invasion, or with extended contra-lateral lymph node metastasis, AgNORs score was significantly higher than in tumors without them, while was not correlated with age or gender of the patients, nor the histological type of the tumor (papillary or follicular). Disease recurrence was observed in one-third of the patients in high AgNOR score group (scored more than mean value +/- standard deviation) when the patients were divided into four groups according to the AgNOR score, and a significantly higher risk for disease recurrence was demonstrated in those cases with high AgNOR score than cases with lower score. These results clearly indicated the usefulness of AgNOR score in selecting the patients at high risk for disease recurrence. All 5 recurrent cases displayed local recurrence in high AgNOR score group, while 5 of 7 cases with low AgNOR score did in the manner of hematological metastasis. In conclusion, this method was technically simple and accurate giving an exact value in individual cases. Thus, we believe AgNOR score might be clinically applicable as a useful indicator for disease recurrence in DTC.