Human Telomere Reverse Transcriptase Expression Predicts Progression and Survival in Pediatric Intracranial Ependymoma

Abstract

Purpose Pediatric intracranial ependymomas are a heterogeneous group of neoplasms with unpredictable clinical and biologic behavior. As part of ongoing studies to identify potential biologic and therapeutic markers, we analyzed the role of human telomere reverse transcriptase (hTERT; the catalytic subunit of telomerase) expression as a prognostic marker for this disease. Patients and Methods Primary intracranial ependymomas that were resected at our institution between 1986 and 2004 were identified through the pathology and oncology databases. A tissue array was constructed from the patient samples and hTERT expression was evaluated by immunohistochemistry. Twenty-one samples were also analyzed for telomerase activity (telomerase repeat amplification protocol assay). Results Eighty-seven tumors from 65 patients were analyzed. Five-year progression-free survival was 57% (SEM, 12%) and 21% (SEM, 8%) for hTERT-negative and hTERT-positive tumors, respectively (P = .002). Five-year overall survival was 84% (SEM, 7%) and 41% (SEM, 7%) for hTERT-negative and hTERT-positive tumors, respectively (P = .001). There was good correlation between telomerase activity and hTERT expression (κ = 0.637). Multivariate analysis revealed hTERT expression to be the single most important predictor of survival of all known pathologic, clinical, and treatment factors (hazard ratio, 60.4; 95% CI, 6.4 to 561). All four patients with hTERT-negative tumors at relapse are still alive, with median follow-up of 11.2 years. Conclusion In this study, hTERT expression was the strongest predictor of outcome and was independent of other clinical and pathologic prognostic markers. It represents a simple and reliable biologic prognostic factor for intracranial ependymomas. These results should be confirmed in larger prospective trials.