Nucleolar organiser regions as a marker of growth rate in squamous cell carcinoma of the lung.

BACKGROUND The numbers of nucleolar organiser regions (AgNORs) per cell has been considered as an indicator of the cellular proliferative activity. A study was carried out to examine whether AgNOR numbers relate to the growth rate in squamous cell carcinoma of the lung. METHODS AgNORs were stained by a one step silver method, and examined in representative paraffin sections from 45 cases of squamous cell carcinoma of the lung treated by surgical resection of the primary tumour. RESULTS The mean (SD) AgNOR numbers per cell in squamous cell carcinomas (5.3 (0.9)) were significantly higher than those in normal bronchial epithelium (1.2 (0.1)). There was no statistical difference among tumours of different post-surgical stages (stage I = 5.2 (0.8), II = 5.9 (1.4), III A = 5.5 (1.3)). The tumour volume doubling time in these cases ranged from 74 to 208 days (120.7 (40.4)). There was a high inverse correlation between the AgNOR numbers and doubling time. CONCLUSION The AgNOR numbers were related to the growth rate of squamous cell carcinoma of the lung. Thus the AgNOR count could be used as a useful marker for investigating the cellular proliferative activity.