title: Induction of high grade astrocytoma (HGA) by protons:  molecular mechanisms and RBE considerations.
abstract: Protons of a specific energy, 55 MeV, have been found to induce primary high grade astrocytomas (HGA) in the Rhesus monkey (Macaca mulatta). Brain tumors of this type were not induced by protons of other energies (32-2,300 MeV). Induction of HGA has been identified in human patients who have had radiation therapy to the head. We believe that the induction of HGA in the monkey is a consequence of dose distribution, not some unique "toxic" property of protons. Comparison of the human experience with the monkey data indicates the RBE for induction of brain tumors to be about one. It is unlikely that protons cause an unusual change in oncogenic expression, as compared to conventional electromagnetic radiation.
authors.affiliation: Department of Radiology, University of Nebraska Medical Center, Omaha 68144, USA.
authors.forename: G V
authors.initials: GV
authors.lastname: Dalrymple
authors.forename: P K
authors.initials: PK
authors.lastname: Leichner
authors.forename: K A
authors.initials: KA
authors.lastname: Harrison
authors.forename: A B
authors.initials: AB
authors.lastname: Cox
authors.forename: K A
authors.initials: KA
authors.lastname: Hardy
authors.forename: Y L
authors.initials: YL
authors.lastname: Salmon
authors.forename: J C
authors.initials: JC
authors.lastname: Mitchell
mesh_terms: D000818:Animals; D001254:Astrocytoma / Q000209:etiology*; D004307:Dose-Response Relationship, Radiation; D004806:Ependymoma / Q000209:etiology; D006801:Humans; D008253:Macaca mulatta; D009381:Neoplasms, Radiation-Induced; D011522:Protons; D011829:Radiation Dosage; D011839:Radiation, Ionizing; D012062:Relative Biological Effectiveness
chemical_list: D011522:Protons