Survivin expression in intracranial ependymomas and its correlation with tumor cell proliferation and patient outcome

Survivin expression has been described as prognostic factor in various tumor types and has been shown to correlate with cytologic anaplasia in ependymoma. We immunohistochemically studied survivin expression and its association with Ki-67 and topoisomerase IIalpha (TIIalpha) expression and outcome in 63 patients with intracranial ependymoma. Survivin is expressed in a fraction of nuclei of tumor and endothelial cells including mitotic figures. Survivin indices range from 0.6% to 43.2% and correlate with Ki-67 and TIIalpha indices. On average, 62.86% of Ki-67-expressing tumor cell nuclei coexpress survivin, whereas 92.2% of survivin-expressing nuclei coexpress Ki-67. High survivin, Ki-67, and TIIalpha indices univariately correlated with an unfavorable outcome. In multivariate analysis, only the Ki-67 index remained an independent prognostic factor. In ependymoma, survivin is expressed in a subset of proliferating cells. High survivin expression is associated with poor patient outcome. However, the Ki-67 index is a more accurate prognostic marker than the survivin or TIIalpha index.