Bromodeoxyuridine labeling study of intracranial meningiomas: proliferative potential and recurrence

Ninety-six patients with intracranial meningiomas and two with hemangiopericytic variants received a 30-min intravenous infusion of bromodeoxyuridine (BrdUrd), 200 mg/m², before tumor removal. Excised tumor specimens were stained by the indirect immunoperoxidase method to determine the BrdUrd labeling index (LI), or percentage of cells in DNA synthesis. The BrdUrd LI was < 1% in 63 (86.3%) of 73 nonmalignant meningiomas and < 1% in 20 (87%) of 23 malignant meningiomas. Of 23 malignant meningiomas 11 were recurrent tumors; 8 patients had recurrence 3 to 33 months after the study. The recurrence rate was 100% (five of five) in patients whose tumors had a BrdUrd LI > 5%, 44% (11 of 25) in those with a BrdUrd LI 1% to 5%, and 6.1% (4 of 66) in those with an LI < 1%. Thus, meningiomas with a BrdUrd LI > 1% may grow faster and recur more frequently. Among patients with malignant mengngiomas, the mean time to recurrence after the study was 7.5 months in those with a BrdUrd LI > 5% and 20.2 months for those with an LI 1% to 5%. The mean time to recurrence was 97.8 months in patients with nonmalignant meningiomas. Both hemangiopericytic variants were recurrent and showed LIs of 0.5% and 4.1%; the former tumor recurred 8 years after complete resection, while the latter recurred three times in 3.5 years. Thus, the proliferative potential of intracranial meningiomas as reflected by the BrdUrd LI appears to be a prognostic variable that can help to elucidate the biological behavior of individual meningiomas.