Imaging biomarkers of outcome after radiotherapy for pediatric ependymoma.

BACKGROUND AND PURPOSE: Ependymoma is the third most common brain tumor in children. Radiation therapy (RT) is systematically administered after maximum surgical resection, utilizing recent advances in radiation delivery. Imaging can make a significant contribution to improving treatment outcome. This prompted us to look for significant preoperative and postoperative imaging markers for survival.

MATERIAL AND METHODS: We undertook a national retrospective review of 121 patients who had undergone resection followed by RT. Preoperative tumor volumes on T1 and FLAIR images were delineated, together with postoperative hyperintense volumes on FLAIR images. Overall survival (OS) and disease-free survival (DFS) analyses included clinical data and volumes extracted from images.

RESULTS: After a median follow-up of 38.5 months, 80.2% of patients were alive, but 39.7% had experienced at least one event. Statistically significant differences between patients with and without postoperative FLAIR abnormalities were found for both DFS (71.9% vs. 40.3%; p = 0.006) and OS (93.7% vs. 72.4%; p = 0.023) in the univariate analyses, and for OS (p = 0.049) in the multivariate analyses.

CONCLUSIONS: Postoperative FLAIR hyperintensities are a negative prognostic factor for intracranial ependymoma and may be a surrogate for residual disease. They could therefore prove helpful in patients' surgical and radiotherapeutic management.