Practical value of MIB-1 index in predicting behavior of astrocytomas.

ABSTRACT

Background: The MIB-1 labeling index (LI) has proved to be useful in assigning grading and prognosis to astrocytomas. The purpose of our study was to analyze the utility of MIB-1 LI in differentiating astrocytomas of varying grades and the possible relationships of MIB-1 LI with clinical parameters like age and sex. We also wanted to study the prognostic role of MIB-1 index in predicting behavior of astrocytomas. Materials and Methods: Our study included 145 patients with astrocytic tumors of varying grades. Immunolabeling for all patients was done using MIB-1 antibody. Survival data could be obtained for 64 patients. A Mann-Whitney U test was used to test the difference in MIB-1 LI between different histological grades. The univariate analysis was done by the Kaplan-Meier method, and the multivariate analysis for survival was performed using the Cox proportional hazard model. Results: Significant differences were noted in mean MIB-1 LI of high-grade and low-grade diffuse astrocytomas. MIB-1 LI did not vary significantly with age and sex. Univariate analysis showed favorable prognostic factors for low histopathological grade, young patient age and low MIB-1 LI; however, multivariate analysis showed that only histopathological grade had independent prognostic significance. Conclusions: Our study proves that MIB-1 LI is not dependent on factors like age and sex and is solely dependent on histological grade. Though the average level of MIB-1 LI varies considerably in the different grades of astrocytomas, considerable overlap can be observed between them. MIB-1 LI is a very useful adjunct to the histopathological diagnosis and can be of great help in situations where the clinical and radiological findings do not correlate with histological diagnosis.