title: Wide-field pulsed reduced dose rate radiotherapy (PRDR) for recurrent ependymoma in pediatric and young adult patients.
abstract: OBJECTIVE
  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.
  
  
  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.
  
  
  CONCLUSIONS
  In patients with large-volume recurrent ependymoma, re-irradiation with wide-field PRDR is a feasible option.
authors.affiliation: Department of Human Oncology, University of Wisconsin Hospital and Clinics, Paul P Carbone Cancer Center, Madison, WI, USA. pmohindra@uwhealth.org
authors.forename: Pranshu
authors.initials: P
authors.lastname: Mohindra
authors.forename: H Ian
authors.initials: HI
authors.lastname: Robins
authors.forename: Wolfgang A
authors.initials: WA
authors.lastname: Tomé
authors.forename: Lori
authors.initials: L
authors.lastname: Hayes
authors.forename: Steven P
authors.initials: SP
authors.lastname: Howard
mesh_terms: D000293:Adolescent; D000328:Adult; D001932:Brain Neoplasms / Q000401:mortality / Q000532:radiotherapy*; D002648:Child; D002675:Child, Preschool; D018572:Disease-Free Survival; D004806:Ependymoma / Q000401:mortality / Q000532:radiotherapy*; D005260:Female; D006801:Humans; D008297:Male; D009364:Neoplasm Recurrence, Local / Q000532:radiotherapy; D011879:Radiotherapy Dosage; D050397:Radiotherapy, Intensity-Modulated / Q000009:adverse effects / Q000379:methods*; D012189:Retrospective Studies; D016019:Survival Analysis; D055815:Young Adult
keywords: Re-irradiation; ependymoma; pulsed reduced dose-rate radiotherapy