Flow cytometric determination of modal DNA population in relation to proliferative potential of human intracranial neoplasms

Paraffin-embedded specimens of brain tumors from 256 patients who had received an intravenous infusion of bromodeoxyuiridine (BUdR) at the time of craniotomy were analyzed retrospectively by flow cytometry to determine the modal deoxyribonucleic acid (DNA) population. A single G₁ peak was considered to represent a unimodal DNA population; two or more G₁ peaks indicated a multimodal population. Most of the pituitary tumors and moderately anaplastic astrocytomas had unimodal DNA populations, whereas a higher percentage of other slow-growing tumors, such as meningiomas, ependymomas, and neurilemomas, had multimodal populations (46.2%, 50.0%, and 60.0%, respectively). A relatively high percentage of the rapidly growing or highly malignant brain tumors, including highly anaplastic astrocytomas, glioblastomas multiforme, metatatic tumors, and medulloblastomas, also had multimodal populations (52.9%, 48.7%, 57.1%, and 66.7%, respectively). In most tumor groups, however, the percentage of tumors with a multimodal DNA population did not correlate with the BUdR labeling index or with the percentage of BUdR-labeled-S-phase cells. Thus, modal DNA analysis by flow cytometry may provide information about the degree of heterogeneity and the biological behavior of individual brain tumors, but the results do not necessarily correlate with the rate of tumor growth or the prognosis in individual patients.