Comparison of Ki-67/MIB-1 labelling index and histopathological grading of astrocytoma

Astrocytomas are common malignant brain tumours. Ki-67/MIB-1 index serves as an important supplementary tool in the diagnosis and prognosis of human astrocytoma. Methods: Forty (40) cases of various histopathological (WHO) grades of astrocytoma (Pilocytic, diffuse, Anaplastic and Glioblastoma multiforme) were included in this study. Ki-67/MIB-1 labelling index of these tumours was estimated by immunohistochemistry, performed on paraffin sections. Histopathological grading and Ki-67/MIB-1 labelling index were compared. The results were analyzed by one way ANOVA. Results: Out of 40 cases two were diagnosed as pilocytic astrocytoma (WHO grade-1) with a mean Ki-67/MIB-1 labelling index of 0.7±1.4 (range 0.6–0.8%). Thirteen cases were of diffuse astrocytoma (WHO grade II), with a mean Ki-67/MIB-1 labelling index of 3.07±3.7 (range 1–15%). Nine cases were diagnosed as Anaplastic astrocytoma (WHO grade III) with a mean Ki-67/MIB-1 labelling Index of 11.55±7.8 (range 2–35%). Sixteen cases were diagnosed as Glioblastoma multiforme with a mean Ki-67/MIB-1 labelling Index of 14.1±8.9 (range (5–36%). ANOVA showed a significant differences between four compared groups (p=0.003). Conclusion: Immunohistochemical analysis of Ki-67/MIB-1 labelling index increases significantly with increasing grade of malignancy. The Ki-67/MIB-1 labelling index can be used as an adjuvant to histopathological grading for proper diagnosis and grading of astrocytoma especially in borderline cases and in small biopsies. (author)