Prognostic significance of the immunohistochemical index of survivin in glioma: A comparative study with the MIB-1 index

Objective: Survivin has been identified as a protein expressed in cancer cells and a member of the inhibitor-of-apoptosis protein family. Recent studies suggest that the expression of survivin increases during the G2/M phase of the cell cycle, and may be used in clinical prognosis. We examined whether survivin expression in human gliomas would be a correlative of prognosis. Methods: We prepared polyclonal anti-survivin serum to establish a survivin index for stained sections, using an immunohistochemical procedure, according to the method used for scoring MIB-1 index, and then stained 29 paraffin-embedded sections from surgical specimens of 29 patients who were classified into three grades of World Health Organization with the mean age of low grade astocytoma (grade II) being 34.7; anaplastic astrocytoma (grade III), 48.8; and glioblastoma multiform (grade IV), 58.4. Results: On staining with the anti-survivin antiserum, all specimens contained positive cells, but the survivin index was heterogeneous among grades. The mean percentage of immunoreactive cells in each specimen was 70.0 (SD 18.2) in grade II, 81.3 (16.5) in grade III, and 85.0 (13.6) in grade IV. Then we compared the survivin index to the MIB-1 index and found that in low-grade gliomas (grade II and III), the difference in survival times between the high and low survivin indexes was significant (P = 0.007), whereas that between the high and low MIB-1 indexes was not significant (P = 0.092). Conclusion: Survivin is more sensitive marker than MIB-1 for the evaluation of low-grade gliomas in that it helps to predict patient survival. Much larger glioma patient series are needed to validate the findings of our limited study.