Proliferating cell nuclear antigen and Ki-67 immunohistochemistry of oligodendrogliomas with special reference to prognosis

Background. The biologic behavior of oligodendrogliomas is somewhat unpredictable. A supplementary prognostic factor is, therefore, desirable. Methods. Thirty-two pure supratentorial oligodendrogliomas were investigated using proliferating cell nuclear antigen (PCNA) and Ki-67 immunohistochemical analyses. The correlation of PCNA and Ki-67 labeling index (LI) with prognosis were studied, and the correlation of LI with clinical data was evaluated. Results. The PCNA LI had a range of 0-17% (mean, 5.27%; standard deviation [SD] = 4.65), and the Ki-67 LI had a range of 0-29% (mean, 4.19%; SD = 5.66). In general, the PCNA LI seemed to be higher than the Ki-67 LI. The mean survival time was 4.4 years, and 5- and 10-year survival rates were 38% and 19%, respectively. Ki-67 and PCNA staining indicated that patients with a high LI (>3% and >4%, respectively) had a significantly higher mortality, with mean survival time of 23.5 months and 26.2 months, respectively. No significant correlation between LI (or survival) and tumor size, cerebral localization, radiation, resection/biopsy, sex, age, or cytologic atypia was found. Conclusions. The use of Ki-67 and PCNA LI higher than 3% and 4%, respectively, appears reliable as prognostic factors when investigating pure supratentorial oligodendrogliomas.