[A cell kinetic study of human central nervous system tumors with 5-bromodeoxyuridine (BrdU)]

Sixty-six patients with various types of central nervous system (CNS) tumors were given 150-200 mg/m2 of 5-bromodeoxyuridine (BrdU) intravenously at the start of surgery, in order to label DNA synthesizing cells in the tumor with BrdU. The excised tumor specimens were fixed in chilled 70% ethanol for at least 12 hours, embedded in paraffin, and cut into 6-8 mu thick sections. The tissue sections were deparaffinized, denatured with HC1, and stained by indirect peroxidase method using anti-BrdU monoclonal antibody as the first antibody. The percentage of labeled cells among total cells (LI: labeling index) was calculated in each tumor specimen. The average of LIs was over 10% in glioblastoma multiforme, medulloblastoma, and metastatic tumor. On the other hand, the LIs were very low, i.e. less than 1% in most cases of ependymomas, mixed gliomas, and moderately anaplastic astrocytomas. In highly anaplastic astrocytomas, the average of LIs resulted in 7.4%. The LIs of slow-growing tumors, such as pituitary adenomas, meningiomas, acoustic neurinomas, were less than 1%, except in Nelson's syndrome and a few cases of meningiomas. The LIs obtained thus seem to correlate with the clinical behavior of each type of tumor. However, there was still a magnitude of differences in LIs between the tumors which were histopathologically alike. These results indicate that the LI obtained by the immunohistochemical method using anti-BrdU monoclonal antibody may supplement the current histopathological diagnosis in characterizing as well as estimating the biological malignancy of individual CNS tumors.