Pediatric Meduloblastoma and the Prognostic Value of MIB-1 Proliferative Factor

Medulloblastoma is the most common malignant brain tumor in children. The important factors in predicting survival are the extent of disease, proliferation index of the tumor cells, histopathologic class and the age at diagnosis. The percentage of Ki-67 positive cells reflects the proliferation of the cells and is one of the critical factors which determine the growth of the tumor. Monoclonal MIB-1 antibody can be targeted against recombinant Ki-67 and then demonstrated by immunohistochemical methods. Formalin-fixed, paraffin-embedded tissue of 18 pediatric patients with medulloblastoma at Mofid Children Hospital between January 2003 and December 2008 were used to perform Ki-67 (MIB-1) immunohistochemical analysis. Proliferative labeling index (LI) was scored in the tumor cells to determine the extent of proliferation. The mean±SD of MIB-1 LI index was 53%±21% (range 25% to 85%). Kaplan–Meier curves showed that patients with MIB-1 LI <40% had higher 5-year survival than patients with MIB-1 LI> 40% (p=0.04). This difference remained statistically significant in Cox regression analysis. We suggest that MIB-1 LI is helpful as a prognostic factor in predicting survival of patients with pediatric medulloblastoma.