Expression of Ki 67 and P53 immunohistochemical markers in central nervous system astrocytoma

Background : Astrocytic tumors are the most common primary tumors of the central nervous system. Several grading systems are used to grade astrocytomas. The most widely used system is the World Health Organization (WHO) classification (1979, 1993, 2000, and 2007) that grades astrocytomas (I-IV) based on cytological atypia, mitotic activity, vascular proliferation, and necrosis : pilocytic astrocytoma (grade I), diffuse astrocytoma (grade II), anaplastic astrocytoma (grade III), and glioblastoma (grade IV). Objectives : The aim of this study is to evaluate p53 over expression , Ki-67 expression in astrocytomas and Correlate these two markers with histologic grade of astrocytomas. Methods : Formalin fixed, paraffin-embedded blocks from 40 patients with brain astrocytoma included in this retrospective study. LSAB (Labeled Strept-Avidin, Biotin) method was employed for immunohistochemical detection of Ki – 67 and P53. Results : P53 was detected in (25 %) of the cases and was significantly positively correlated with grade IV. Ki-67 labeling index was (> 5 %) in (50 %) of the cases. Both biomarkers were positively correlated with each other, and the grade of astrocytoma ; however, Ki67 is a better marker for differentiating (diagnostic marker) between the grades of astrocytoma than p53. Conclusion : P53 overexpression and ki-67 expression plays an important role in pathogenesis of astrocytoma evolution, as they positively associated with higher tumor grade.