title: Proton versus photon radiation therapy for patients with high-risk neuroblastoma: the need for a customized approach.
abstract: BACKGROUND
  Proton therapy for treatment for high-risk neuroblastoma may offer sparing of organs at risk (OAR) when compared to intensity-modulated X-ray therapy (IMXT).
  
  
  METHODS
  Double-scattered proton plans and IMXT plans delivering 2,160 cGy to the primary tumor site and other residual disease were developed for 13 consecutive HR-NBL patients. Radiation doses to target volumes and OAR were calculated to determine the optimal modality for each.
  
  
  RESULTS
  All patients received radiation (5/13 ≥ 2 sites). No patient has experienced local recurrence or clinical organ toxicity. Coverage was excellent using both protons and IMXT: median % dose delivered to 95% clinical target volume was 99% and 100%, respectively. For nine patients with lateralized disease, proton therapy offered sparing of the contralateral kidney both with regard to median dose and dose to 20% (median <1 cGy vs. 362 cGy, P = 0.01; median 100 cGy vs. 634 cGy, P = 0.02, respectively). Proton therapy did not reduce ipsilateral kidney dose, and for 2 select patients with lateralized disease IMXT improved overall bilateral renal sparing. Proton therapy improved median bowel (median 33 cGy vs. 590 cGy, P = 0.01), total body (median <1 cGy vs. 30 cGy, P = 0.15), and liver dose (median <1 cGy vs. 529, P < 0.001). When chest RT was required, proton therapy decreased median heart dose and mean lung dose.
  
  
  CONCLUSIONS
  For most patients (11/13), proton therapy offered the optimal combination of target coverage and organ sparing, and is a feasible treatment for HR-NBL. We recommend a customized approach with careful evaluation of renal dosimetry; IMXT may be preferred for select patients.
authors.affiliation: Department of Radiation Oncology, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA. hill@uphs.upenn.edu
authors.forename: Christine
authors.initials: C
authors.lastname: Hill-Kayser
authors.forename: Zelig
authors.initials: Z
authors.lastname: Tochner
authors.forename: Stefan
authors.initials: S
authors.lastname: Both
authors.forename: Robert
authors.initials: R
authors.lastname: Lustig
authors.forename: Anne
authors.initials: A
authors.lastname: Reilly
authors.forename: Naomi
authors.initials: N
authors.lastname: Balamuth
authors.forename: Richard
authors.initials: R
authors.lastname: Womer
authors.forename: John
authors.initials: J
authors.lastname: Maris
authors.forename: Stephen
authors.initials: S
authors.lastname: Grupp
authors.forename: Rochelle
authors.initials: R
authors.lastname: Bagatell
mesh_terms: D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D009447:Neuroblastoma / Q000532:radiotherapy*; D061766:Proton Therapy / Q000379:methods; D011879:Radiotherapy Dosage; D014964:X-Ray Therapy / Q000379:methods
keywords: high-risk neuroblastoma; neuroblastoma; proton therapy; radiation