Abstract
The malignancy of a brain tumor has mainly been assessed by histopathological examination of the tumor. However, the use of more quantitative criteria than histological findings to evaluate the malignancy is anticipated. In the present study, the author examined the amount of nuclear DNA by microfluorometric analysis and the Ki-67 labelling index, using immunohistochemistry, in 132 cases with various brain tumors. These results were compared with the histopathologic findings of the tumors to assess the validity of these criteria as indicators of tumor malignancy. The DNA histogram showed an increase in the DNA index and a diversity of ploidy patterns in association with an increase in the histological grade of tumor malignancy. The DNA index and ploidy diversity were correlated with cellular pleomorphism, mitotic figures, and vascular endothelial proliferation. The Ki-67 labelling index also showed a positive correlation with the histological grade of tumor malignancy. There was no significant relationship between Ki-67 labelling and nuclear DNA parameters. This means that the two indices are mutually independent criteria in the evaluation of tumor growth potential. It is suggested that microfluorometric DNA analysis shows tumor cell abnormalities at chromosomal and genetic levels, and that the Ki-67 labelling index indicates the size of the growth fraction of a tumor. It is concluded that these two parameters are useful in evaluation of the proliferative potential of a given brain tumor.
