Wide-field pulsed reduced dose rate radiotherapy (PRDR) for recurrent ependymoma in pediatric and young adult patients.

Aim: This retrospective analysis evaluates feasibility of wide-field re-irradiation using pulsed reduced dose rate (PRDR) technique in patients with recurrent ependymoma. PRDR employs a dose rate of 6 cGy/min, as opposed to 400-600 cGy/min for conventional radiation, allowing for enhanced normal tissue repair. Patients and Methods: Five patients with recurrent ependymoma having eight lesions (two brain, six spinal cord) were treated with PRDR. Progression-free survival (PFS) and overall survival (OS) were estimated by Kaplan Meier method. Results: The median interval between two radiation courses was 58 months (range: 32-212 months). The median PRDR dose was 40 Gy (range: 30.6-54 Gy) with a median cumulative lifetime dose of 105.2 Gy (range: 90-162.4 Gy). At a median post- PRDR follow-up of 64 months, estimated 4-year OS and PFS from PRDR was 60% and 35.7%, respectively. None of the patients developed necrosis on serial magnetic resonance imaging scans, and only one patient had progressive mild radiculopathy. Conclusion: In patients with large-volume recurrent ependymoma, re-irradiation with wide-field PRDR is a feasible option. Ependymomas are rare neuro-epithelial tumors that arise from ependymal cells lining the ventricles and cerebro-spinal fluid (CSF) outflow track. Standard treatment recommendation includes maximal safe resection followed by consideration of adjuvant radiotherapy (RT) based on pathological findings. Treatment options for recurrent