title: Definitive treatment of leptomeningeal spinal metastases in children.
abstract: BACKGROUND
  Uniquely in children, the existence of leptomeningeal spinal metastases does not confer a uniformly grave prognosis. Although the radiation tolerance of the spinal cord is of significant concern in these cases, the chemo- and radiosensitivity of these lesions argues for an aggressive approach where possible.
  
  
  METHODS
  The records of the Indiana University Health Proton Therapy Center were reviewed for patients undergoing proton beam therapy with curative intent for LSM between January 1, 2004 and July 7, 2012. Patients with microscopic disease only on LP were not included. Particulars of therapy, including dose, field sizes, toxicities, and outcomes were collated.
  
  
  RESULTS
  Twenty-two children received therapy as described, of median age 5 years (range 1.1-17.1). Patients had medulloblastoma (n = 9), ATRT (n = 4), ependymoma, and PNET (n = 3 each). Five lesions (23%) were chemo-recurrent, though no patient had prior radiation to the spine. Median follow-up was 14 months (range 4-33) for all living patients. Fifteen (68%) children continued to have local control at last follow-up visit. Median dose was 37.8 Gy (range 21.6-54 Gy). Eight patients with chemo-recurrent disease or diffuse cord seeding did poorly, with local control and overall survival achieved in four. The 12-month overall survival was 68% with grade 1 skin erythema as the most frequent toxicity.
  
  
  CONCLUSIONS
  We describe a cohort of LSM patients treated with RT with definitive intent, and the only available data from the proton environment. Durable response is possible for these children in over two-thirds of cases. Significant toxicity was infrequent using proton radiotherapy and these fractionation schemes.
authors.affiliation: Department of Radiation Oncology, Indiana University School of Medicine, Indianapolis, Indiana; IU Health Proton Therapy Center, Bloomington, Indiana.
authors.forename: Geoffrey L
authors.initials: GL
authors.lastname: Ray
authors.forename: Jeffrey C
authors.initials: JC
authors.lastname: Buchsbaum
authors.forename: Kevin P
authors.initials: KP
authors.lastname: McMullen
authors.forename: R Victor
authors.initials: RV
authors.lastname: Simoneaux
authors.forename: Matthew
authors.initials: M
authors.lastname: Hines
authors.forename: James G
authors.initials: JG
authors.lastname: Douglas
authors.forename: Peter A S
authors.initials: PA
authors.lastname: Johnstone
mesh_terms: D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D055756:Meningeal Carcinomatosis / Q000401:mortality / Q000532:radiotherapy*; D061766:Proton Therapy / Q000009:adverse effects / Q000379:methods*; D013116:Spinal Cord / Q000473:pathology*
keywords: leptomeningeal spinal metastases; pediatric oncology; protons; radiation oncology