The prognostic significance of MIB-1, p53, and DNA flow cytometry in completely resected primary meningiomas.

BACKGROUND: Despite the availability of clinical and pathologic parameters of prognosis, the behavior of an individual meningioma may be difficult to predict. In a recent review of gross totally resected (GTR) meningiomas, the authors found strong associations between microscopic brain invasion, increased mitotic rate (> or = 4/10 high-power fields), the presence of at least 3 of 4 morphologic variables (sheeting, hypercellularity, macronucleoli, and small cells), and decreased recurrence free survival (RFS). In this study, they assessed the prognostic value of three ancillary techniques: DNA flow cytometry, MIB-1 labeling, and p53 protein expression.

METHODS: The authors evaluated primary GTR meningiomas from 425 patients with DNA flow cytometry, immunostaining for MIB-1, and determination of p53 protein expression. The patients were followed until death or for a median of 8.9 years.

RESULTS: An MIB-1 labeling index (LI) of > or = 4.2%, identified in 8% of cases, was strongly associated with decreased RFS in univariate analysis (P=0.0001). Fourteen percent contained aneuploid cell populations, and 48% exhibited a p53 LI of >10%. Neither variable was associated with decreased RFS. Further analysis revealed a close association between MIB-1 LI and mitotic index, the latter being the parameter of greatest significance in multivariate analysis.

CONCLUSIONS: MIB-1 LI is a useful adjunct to routine histologic evaluation of meningiomas and appears to be of greatest value in the evaluation of tumors exhibiting borderline atypia. In contrast, our data suggest that, regarding patients with primary GTR meningiomas, neither flow cytometry nor p53 immunohistochemistry provides useful prognostic information.