p53 Expression and Ki-67 Labeling Index in Brain Tumor with Special Reference to Tumor and Histologic Grade

ABSTRACT

Mutation in the p53 suppressor gene is the most common genetic alteration found in human cancers including primary brain tumors. Ki-67 labeling index(LI) is known to be a marker of proliferating activity. The purpose of this study was to verify whether an immunohistochemical expression of p53 antibody and Ki-67 LI could be related to different clinicopathologic parameters including histologic grade, size, invasiveness and recurrence of the brain tumors. Materials were based on the 147 surgically resected brain tumors during the last two years. Of the 147 brain tumors, there were 35 astrocytic tumors, 35 meningiomas, 10 oligodendrogliomas, 7 craniopharyngiomas, 5 dysembryoplastic neuroepithelial tumors, 4 medulloblastomas, 5 ependymomas, 23 pituitary adenomas, 9 schwannomas, and 14 other brain tumors. The p53 expression and Ki-67 LI were higher in malignant brain tumors including astrocytic tumors, medulloblastoma, PNET and gliosarcoma. The p53 positivity was correlated with histologic grades and tumor recurrence. The brain tumors with a high Ki-67 LI(>6%) also showed a close relationship to a higher histologic grading, radiological invasiveness and recurrence. There was no evident correlation with the age and tumor size with p53 expression and Ki-67 LI. These results suggest that p53 overexpression and high proliferation potential of the tumor cells are associated with the higher histologic grade and aggressive clinical course in the central nervous system tumors.