Diagnostic and Prognostic Role of Ki67 Immunostaining in Human Astrocytomas Using Four Different Antibodies

Objective: Astrocytomas have an inherent tendency to progress, and histopathological examination and grading do not always identify these subsets of tumors. The aim of this study was therefore to investigate whether different Ki67 antibodies could assist in the diagnostic and prognostic evaluation of these tumors.

Material And Methods: Forty-one cerebral astrocytomas, graded according to the latest criteria of the World Health Organization, were included in the study: 22 diffuse fibrillary astrocytomas, 10 anaplastic astrocytomas and 9 glioblastomas. Standard immunohistochemical analyses were performed using 4 different commercially available Ki67 antibodies. The immunohistochemical data were correlated with the clinical course.

Results: There were positive correlations between the proliferation indices (PI) obtained with the different Ki67 antibodies. The Ki67 PIs increased significantly with increasing malignancy grade, and the antibodies discriminated well between low- (grade II) and high-grade tumors (grade III and IV). For the entire tumor material, the use of median values as cutoff divided the astrocytomas into 2 groups: those tumors with the higher Ki67 PIs had significantly poorer prognosis than those with lower indices.

Conclusions: Ki67 immunostaining serves as an important supplementary tool in the diagnostic and prognostic evaluation of human astrocytomas.