title: Comparison of risk of radiogenic second cancer following photon and proton craniospinal irradiation for a pediatric medulloblastoma patient.
abstract: Pediatric patients who received radiation therapy are at risk of developing side effects such as radiogenic second cancer. We compared proton and photon therapies in terms of the predicted risk of second cancers for a 4 year old medulloblastoma patient receiving craniospinal irradiation (CSI). Two CSI treatment plans with 23.4 Gy or Gy (RBE) prescribed dose were computed: a three-field 6 MV photon therapy plan and a four-field proton therapy plan. The primary doses for both plans were determined using a commercial treatment planning system. Stray radiation doses for proton therapy were determined from Monte Carlo simulations, and stray radiation doses for photon therapy were determined from measured data. Dose-risk models based on the Biological Effects of Ionization Radiation VII report were used to estimate the risk of second cancer in eight tissues/organs. Baseline predictions of the relative risk for each organ were always less for proton CSI than for photon CSI at all attained ages. The total lifetime attributable risk of the incidence of second cancer considered after proton CSI was much lower than that after photon CSI, and the ratio of lifetime risk was 0.18. Uncertainty analysis revealed that the qualitative findings of this study were insensitive to any plausible changes of dose-risk models and mean radiation weighting factor for neutrons. Proton therapy confers lower predicted risk of second cancer than photon therapy for the pediatric medulloblastoma patient.
authors: Graduate School of Biomedical Sciences, The University of Texas at Houston, Houston, TX, USA.
authors: Rui
authors: R
authors: Zhang
authors: Rebecca M
authors: RM
authors: Howell
authors: Annelise
authors: A
authors: Giebeler
authors: Phillip J
authors: PJ
authors: Taddei
authors: Anita
authors: A
authors: Mahajan
authors: Wayne D
authors: WD
authors: Newhauser
mesh_terms: D000465:Algorithms; D016543:Central Nervous System Neoplasms / Q000473:pathology / Q000532:radiotherapy*; D002675:Child, Preschool; D061888:Craniospinal Irradiation / Q000009:adverse effects*; D004307:Dose-Response Relationship, Radiation; D006801:Humans; D008297:Male; D008527:Medulloblastoma / Q000473:pathology / Q000532:radiotherapy*; D009010:Monte Carlo Method; D009381:Neoplasms, Radiation-Induced / Q000175:diagnosis*; D016609:Neoplasms, Second Primary / Q000175:diagnosis / Q000209:etiology*; D061766:Proton Therapy / Q000009:adverse effects* / Q000379:methods; D050397:Radiotherapy, Intensity-Modulated / Q000379:methods; D012306:Risk; D014018:Tissue Distribution; D014057:Tomography, X-Ray Computed / Q000379:methods