Prognostic relevance of DNA flow cytometry in oligodendroglioma

In a retrospective study of 85 cases, the prognostic value of DNA flow cytometry in oligodendrogliomas was evaluated. Paraffin-embedded material was processed for flow cytometry, and the survival rates of the patients with DNA diploid, aneuploid, and tetraploid tumors were compared using analysis of variance. In addition, the mitotic index was correlated with the results of flow cytometry. Finally, the results of flow cytometry, histopathologic grading, and counting mitoses were tested for dependency. Thirty-one percent of the tumors were diploid, 39% were tetraploid, and 31% were aneuploid. The results of the DNA flow cytometry did not correlate with the survival times (P = 0.798) or with tumor degree. In contrast, the number of mitoses (P less than 0.05), and the grades of the grading system of Smith (P less than 0.003) had relevance for the prognosis. No correlation between flow cytometry, histopathologic grading, and mitotic index was found. It is concluded that flow cytometry has no value in predicting the biologic behavior of oligodendrogliomas, whereas the number of mitoses is a valuable prognostic parameter and thus is considered to be incorporated into the grading system for oligodendrogliomas.