Clinical and histopathological analysis of proliferative potentials of recurrent and non-recurrent meningiomas.

Proliferative potentials of meningiomas from 127 patients were examined immunohistochemically using the anti-Ki-67 monoclonal antibody, MIB-1, on paraffin sections, and the correlation among MIB-1 staining index (SI), histopathological finding, and clinical course of the disease was analyzed retrospectively. The mean MIB-1 SI of 50 male patients with meningioma was 5.5%, whereas that of 77 female patients was 2.7%. Higher MIB-1 SI were observed for younger patients. These age- and sex-related differences in MIB-1 SI were statistically significant. The patients were assigned to one of three groups: those with non-recurrent meningioma (n = 73); those with recurrent meningioma in whom the specimens obtained during the initial surgery were used to calculate the MIB-1 SI (n = 21); and those with recurrent meningioma for whom the specimens obtained during the surgery for recurrent tumors were used to calculate the MIB-1 SI (n = 33). The mean MIB-1 SI in these patients were 1.6%, 3.6%, and 8.8%, respectively, and there were statistically significant differences among these three groups. Statistical analyses reveal that meningiomas with a MIB-1 SI of 3% or more have a significantly high tendency for recurrence during the clinical courses, especially within the first 10-year follow-up periods. Moreover, there is statistically significant correlation between MIB-1 SI and recurrence in each Simpson's grade. The time interval to the next recurrence for recurrent meningiomas is associated with the proliferative potential represented by the MIB-1 SI, and a correlation equation has been proposed to predict the date of the next recurrence. Analyses on cellularity of meningiomas revealed no statistically significant difference in cellularity between non-recurrent and recurrent meningiomas. There was no statistically significant relationship between cellularity and MIB-1 SI of meningiomas. In conclusion, examination on proliferative potentials of meningiomas using MIB-1 SI is very important for biological and histopathological analyses and the prediction of future recurrence.