Stereotactic radiosurgery for pediatric recurrent intracranial ependymomas

Abstract

Object To evaluate the role of stereotactic radiosurgery (SRS) in patients with recurrent or residual intracranial ependymomas after resection and fractionated radiation therapy (RT), the authors assessed overall survival, distant tumor relapse, progression-free survival (PFS), and complications. Methods The authors retrospectively reviewed the records of 21 children with ependymomas who underwent SRS for 32 tumors. There were 17 boys and 4 girls with a median age of 6.9 years (range 2.9–17.2 years) in the patient population. All patients underwent resection of an ependymoma followed by cranial or neuraxis (if spinal metastases was confirmed) RT. Eleven patients had adjuvant chemotherapy. Twelve patients had low-grade ependymomas (17 tumors), and 9 patients had anaplastic ependymomas (15 tumors). The median radiosurgical target volume was 2.2 cm3 (range 0.1–21.4 cm3), and the median dose to the tumor margin was 15 Gy (range 9–22 Gy). Results Follow-up imaging demonstrated therapeutic control in 23 (72%) of 32 tumors at a mean follow-up period of 27.6 months (range 6.1–72.8 months). Progression-free survival after the initial SRS was 78.4%, 55.5%, and 41.6% at 1, 2, and 3 years, respectively. Factors associated with a longer PFS included patients without spinal metastases (p = 0.033) and tumor volumes < 2.2 cm3 (median tumor volume 2.2 cm3, p = 0.029). An interval ≥18 months between RT and SRS was also associated with longer survival (p = 0.035). The distant tumor relapse rate despite RT and SRS was 33.6%, 41.0%, and 80.3% at 1, 2, and 3 years, respectively. Factors associated with a higher rate of distant tumor relapse included patients who had spinal metastases before RT (p = 0.037), a fourth ventricle tumor location (p = 0.002), and an RT to SRS interval < 18 months (p = 0.015). The median survival after SRS was 27.6 months (95% CI 19.33–35.87 months). Overall survival after SRS was 85.2%, 53.2%, and 23.0% at 1, 2, and 3 years, respectively. Adverse radiation effects developed in 2 patients (9.5%). Conclusions Stereotactic radiosurgery offers an additional option beyond repeat surgery or RT in pediatric patients with residual or recurrent ependymomas after initial management. Patients with smaller-volume tumors and a later recurrence responded best to radiosurgery.