Proliferative potential of human brain tumours as assessed by nucleolar organizer regions (AgNORs) and Ki67-immunoreactivity.

Two proliferation markers, silver stained nucleolar organizer regions (AgNOR) and immunoreactivity with Ki-67, were used to assess the proliferative activity in 80 smear preparations from neurosurgically removed intracranial tumours. These included 45 gliomas, 18 meningiomas, 8 metastases and 9 others. We found a remarkably close correlation between the results obtained with both methods. Increasing malignancy, as determined by conventional grading, was paralleled by an increase in the growth fraction and the number of nucleolar organizer regions. Linear regression analysis yielded the following equation: AgNORs/cell = 0.35 x L1 (Ki-67) + 3.24, with a correlation coefficient of rs = 0.53 (Spearman rank correlation test, p less than 0.0001). Thus, both the Ki-67 L1 and the AgNOR technique appear suitable for estimating the proliferative potential in smear preparations of human intracranial neoplasms. The AgNOR technique may be particularly useful for application to stereotaxic biopsies since it can easily be performed on minute tumour samples.