title: Radiosensitizing effect of carbogen breathing during pulsed irradiation of the rat R1H tumor.
abstract: The objective of the present study was to investigate the radiosensitizing effect of carbogen breathing during pulsed x-ray irradiation in an experimental tumor model. Rat R1H rhabdomyosarcoma tumors were irradiated with 36 Gy total dose in 1 Gy high dose rate pulses, either hourly repeated, or in an 'office hours' protocol with irradiation-free overnight intervals. With the hourly, pulsed irradiation scheme, tumor growth delay (TGD) was significantly increased from 24.4+/-0.7 days in air-breathing animals to 29.0+/-0.9 days in animals breathing carbogen during irradiation. With irradiation during office hours, the TGD was shortened, and carbogen was less effective. The data show that carbogen acts as a radiosensitizer when applied during pulsed irradiation. Translation of the experimental data to clinical practice indicates that hyperoxygenation of the tumor during pulsed dose rate (PDR) or high dose rate (HDR) brachytherapy might enhance the tumor response of patients.
authors.affiliation: Department of Radiation Oncology, VU University Medical Center, Amsterdam, The Netherlands. p.sminia.radbiol@med.vu.nl
authors.forename: P
authors.initials: P
authors.lastname: Sminia
authors.forename: K A
authors.initials: KA
authors.lastname: Hartmann
authors.forename: C J
authors.initials: CJ
authors.lastname: Schneider
authors.forename: U M
authors.initials: UM
authors.lastname: Carl
authors.forename: A J
authors.initials: AJ
authors.lastname: van der Kleij
authors.forename: B J
authors.initials: BJ
authors.lastname: Slotman
authors.forename: M C
authors.initials: MC
authors.lastname: Huishof
mesh_terms: D000280:Administration, Inhalation; D000818:Animals; D001918:Brachytherapy; D002245:Carbon Dioxide / Q000008:administration & dosage / Q000494:pharmacology*; D019583:Dose Fractionation, Radiation; D008297:Male; D009374:Neoplasms, Experimental; D010100:Oxygen / Q000008:administration & dosage / Q000494:pharmacology*; D011838:Radiation-Sensitizing Agents / Q000008:administration & dosage / Q000494:pharmacology*; D051381:Rats; D012208:Rhabdomyosarcoma / Q000473:pathology / Q000532:radiotherapy*
chemical_list: D011838:Radiation-Sensitizing Agents; D002245:Carbon Dioxide; C011700:carbogen; D010100:Oxygen