Significance of MIB-1, PCNA indices, and p53 protein over-expression in intramedullary tumors of the spinal cord.

Due to the low incidence of intramedullary spinal cord tumors there have been few reports considering its proliferative kinetics. In this study, expression of two cell cycle related antigens (PCNA and MIB-1) were immunohistochemically examined by the percentage of positively stained cells were recorded as PCNA and MIB-1 indices. In addition, over-expression of p53 protein was also investigated in 19 cases of intrameduallary spinal cord tumors. In astrocytic tumors and ependymomas, statistically significant correlations were observed between PCNA and MIB-1 indices (R = 0.98). In hemangioblastoma cases, a similar correlation was not observed between PCNA and MIB-1 indices. The MIB-1 indices of hemangioblastoma cases were less than 1.56 while PCNA indices were more than 14.63 despite long-term survival occurred in all cases. The PCNA index in hemangioblastoma was significantly greater (p < 0.01) than all other types of tumors except for glioblastomas. Thus, interpretation of PCNA index must be made with caution in regard to the subgroup of the tumor histology. Over-expression of the p53 protein was observed only in glioblastoma cases. The MIB-1 index appears to be a useful method for predicting the outcome of all cases with intramedullary tumors of the spinal cord.