AgNOR staining may reflect the growth potential of pilocytic astrocytomas

The value of AgNOR staining as a tumor biological marker was tested in 26 c hildren with pilocytic astrocytomas (20) and fibrillary astrocytomas (6). A ll patients were surgically treated and then followed up by periodic MRI or CT scans. Follow-up ranged from 8 to 84 months, with a mean of 44 months. AgNOR expression was determined by using semi-automated computer-assisted s urface area measurements. AgNOR values ranged from 1.4 to 81.4 mu m(2) per cell, with a mean of 26.6 and a median of 15.2. The median value was taken as a "cut-off" score separating two groups of patients with low and high Ag NOR scores. Of the 13 patients in the low scoring group, 8 had total resect ions without recurrence, 3 had stable residual tumors, I had regressing res idual tumor after irradiation and 1 had a recurrence 5 years after neurorad iologically complete resection of a fibrillary astrocytoma. In the group wi th high AgNOR scores only 2 patients had total resections without recurrenc e; 5 had stable residual tumors and 6 had residual tumors that showed progr ession, all within 1 year after surgery. Among the patients with classic ju venile pilocytic astrocytomas of the cerebellum 7 had residual tumor, which progressed in 2 patients, both of whom had high AgNOR scores. Among 7 pati ents with optic/hypothalamic tumors the 3 with rapidly progressing tumors a ll had very high AgNOR scores. The determination of AgNOR expression might be helpful in selection of patients with residual tumor after surgery, who may benefit from additional chemotherapy or (stereotactic) radiation therap y.