Prognostic significance of MIB-1, p53, and bcl-2 immunoreactivity in meningiomas

Sixty biopsy specimens of meningiomas, including 37 benign, 10 atypical, and 13 malignant meningiomas, were examined immunohistochemically using the monoclonal antibodies MIB-1 (a cell proliferation marker), p53, and bcl-2 (two apoptosis-associated markers). Benign meningiomas were subdivided into two groups: group 1, 29 tumors without recurrence; and group 2, eight tumors with recurrence after complete surgical resection. The mean MIB-1 labeling index (LI) values+/-SD were 1.3+/-3.2% for the benign, 9.3+/-6.9% for the atypical, and 15.0+/-16.9% for the anaplastic meningiomas. The mean MIB-1 LI+/-SD in group 1 tumors (n = 29) was 1.06+/-1.15%, and in group 2 tumors (n = 8), 2.3+/-4.76% (P = .028). p53 protein expression was found in 10.8% of the benign (10.34% of group 1 and 12.5% of group 2), 50% of the atypical, and 77% of the anaplastic meningiomas. bcl-2 protein expression was observed in 21.6% of the benign, 20% of the atypical, and 46.1% of the anaplastic meningiomas. Among the benign meningiomas, group 2 tumors expressed significantly more often bcl-2 protein (62.5%) than group 1 neoplasms (10.3%). Our results indicate that (1) in meningiomas, a good correlation exists between histological grading, MIB-1 and p53 protein expression, and (2) in benign meningiomas, the presence of bcl-2 protein expression together with high MIB-1 LI are associated with unfavorable prognosis of the disease.