Background: Meningiomas are benign tumors that can be cured by surgical removal. However, tumors located deeply within or close to vital structures cannot be removed completely and require repeated surgery. This study was designed to clarify whether immunohistochemical study using MIB-1 monoclonal antibody is useful for determining the rate of regrowth for this tumor.
Methods: Tumor volume doubling time (Td) was measured by using computed tomography or magnetic resonance imaging neuroimages during 29 different follow-up periods after surgery. MIB-1 monoclonal antibody was used to stain Ki-67 proliferating cell antigen in surgical specimens, and the MIB-1 staining index (SI) was determined independently of neuroimaging analysis. These two values and other clinical parameters were analyzed statistically.
Results: The Td values varied from 19-6830 days (median, 350 days); the Td values were <365 days in 15 cases, 365-730 days in 8 cases, and >730 days in 6 cases. There was no significant correlation between age and Td value, but all 6 patients whose Td values were >2 years were age >50. There was a strong inverse correlation between log(Td) and MIB-1 SI (P < 0.001). In three cases, more than three surgical procedures were performed for tumor recurrence. The MIB-1 values did not increase at the time of the first recurrence but increased at later recurrences. The calculated Td values also were not shortened until the second recurrence.
Conclusions: Using the MIB-1 SI makes it possible to predict the regrowth potential of a tumor after initial surgery.