title: Predicted risks of second malignant neoplasm incidence and mortality due to secondary neutrons in a girl and boy receiving proton craniospinal irradiation.
abstract: The purpose of this study was to compare the predicted risks of second malignant neoplasm (SMN) incidence and mortality from secondary neutrons for a 9-year-old girl and a 10-year-old boy who received proton craniospinal irradiation (CSI). SMN incidence and mortality from neutrons were predicted from equivalent doses to radiosensitive organs for cranial, spinal and intracranial boost fields. Therapeutic proton absorbed dose and equivalent dose from neutrons were calculated using Monte Carlo simulations. Risks of SMN incidence and mortality in most organs and tissues were predicted by applying risks models from the National Research Council of the National Academies to the equivalent dose from neutrons; for non-melanoma skin cancer, risk models from the International Commission on Radiological Protection were applied. The lifetime absolute risks of SMN incidence due to neutrons were 14.8% and 8.5%, for the girl and boy, respectively. The risks of a fatal SMN were 5.3% and 3.4% for the girl and boy, respectively. The girl had a greater risk for any SMN except colon and liver cancers, indicating that the girl's higher risks were not attributable solely to greater susceptibility to breast cancer. Lung cancer predominated the risk of SMN mortality for both patients. This study suggests that the risks of SMN incidence and mortality from neutrons may be greater for girls than for boys treated with proton CSI.
authors.affiliation: Department of Radiation Physics, The University of Texas M D Anderson Cancer Center, Houston, TX 77030, USA. ptaddei@mdanderson.org
authors.forename: Phillip J
authors.initials: PJ
authors.lastname: Taddei
authors.forename: Anita
authors.initials: A
authors.lastname: Mahajan
authors.forename: Dragan
authors.initials: D
authors.lastname: Mirkovic
authors.forename: Rui
authors.initials: R
authors.lastname: Zhang
authors.forename: Annelise
authors.initials: A
authors.lastname: Giebeler
authors.forename: David
authors.initials: D
authors.lastname: Kornguth
authors.forename: Mark
authors.initials: M
authors.lastname: Harvey
authors.forename: Shiao
authors.initials: S
authors.lastname: Woo
authors.forename: Wayne D
authors.initials: WD
authors.lastname: Newhauser
mesh_terms: D016543:Central Nervous System Neoplasms / Q000532:radiotherapy*; D002648:Child; D005260:Female; D006801:Humans; D008297:Male; D008527:Medulloblastoma / Q000532:radiotherapy; D008954:Models, Biological; D009010:Monte Carlo Method; D009381:Neoplasms, Radiation-Induced / Q000209:etiology* / Q000401:mortality; D017599:Neuroectodermal Tumors / Q000532:radiotherapy; D009502:Neutrons / Q000009:adverse effects*; D061766:Proton Therapy; D011522:Protons / Q000009:adverse effects; D011879:Radiotherapy Dosage; D012306:Risk; D012737:Sex Factors; D012886:Skull / Q000528:radiation effects*; D013131:Spine / Q000528:radiation effects*
chemical_list: D011522:Protons