Comparative analysis of the precision of various methods for calculating proliferative activity (Ki67) in glioblastomas taking into account their heterogeneity

INTRODUCTION: Glioblastomas are the most common malignant tumors of the nervous system in adults. In modern clinical practice, the assessment of the proliferative activity index by ki-67 in glial neoplasms is widely used. This article evaluates and describes the features of the interpretation of ki-67 values in the morphological diagnosis of gliomas.

PURPOSE: To evaluate the morphological criteria of intratumoral heterogeneity of glioblastomas, to determine the variability of nuclear marker values both between specialists and using different methods.

MATERIALS AND METHODS: 43 fragments from the central and marginal sections from 9 patients with glioblastomas who underwent surgical treatment at the N.N. prof. A. L. Polenov. Immunohistochemical study was performed with primary antibodies to GFAP (to confirm glial tumor differentiation) and Ki-67 (to assess proliferative activity). The level of proliferative activity for Ki-67 in each glass was calculated by two morphologists by a semi-automatic method using the ImageJ program, and also without the use of additional software in 5 fields of view at a magnification of x400, taking into account the average and maximum values. Statistical analysis was performed using the Statistica v 10 program.

RESULTS: a higher level of proliferative activity was found in the central part of glioblastomas. In the predominance of necrosis foci, relatively low values of proliferative activity for glioblastoma were revealed. In our laboratory, a comparative analysis of the calculation of the proliferative activity index by different pathologists did not reveal significant differences in the data obtained (p<0.05).

CONCLUSIONS: for morphological study, it is recommended to take biological material from the central metabolically active areas of gliomas. In cases of analysis of a small volume of material, the value of the level of proliferative activity increases. If the value of ki-67 is more than 10 %, the interpretation of the morphological picture of malignant astrocytoma towards glioblastoma is recommended. Semi-automatic and automatic calculation of proliferative activity significantly speeds up the determination of the Ki-67 index. The results obtained by counting through the eyepieces of the microscope do not differ from the counting and coincide with the data obtained by the semi-automatic method.

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