title: Combination therapy with 1,3-bis(2-chloroethyl)-1-nitrosourea and low dose rate radiation in the 9L rat brain tumor and spheroid models: implications for brain tumor brachytherapy.
abstract: We studied the effects of combination treatment with 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU) and low dose rate radiation in the 9L rat brain tumor in vivo model and the 9L multicellular tumor spheroid model. F-344 rats bearing intracerebral 9L gliosarcomas were implanted with removable 125I sources. Minimal (peripheral) tumor doses of 6387 rad produced an increased life-span (ILS) of 28% over that of control rats implanted with dummy sources, BCNU alone (13.3 mg/kg) produced in an ILS of 67%, and combination treatment with BCNU and implanted 125I sources produced an ILS of 167%. As measured by a colony-forming efficiency assay, the greatest cell kill in 9L spheroids occurred when BCNU was administered 24 hours before irradiation from a 137Cs source at a low dose rate of 5 rad/minute. At a higher dose rate of 210 rad/minute, the time dependence of the effects of combination treatment was identical and therefore independent of dose rate.
mesh_terms: D000818:Animals; D001918:Brachytherapy / Q000379:methods*; D001932:Brain Neoplasms / Q000473:pathology / Q000628:therapy*; D002330:Carmustine / Q000627:therapeutic use*; D003131:Combined Modality Therapy; D005625:Frontal Lobe / Q000473:pathology; D005910:Glioma / Q000473:pathology / Q000628:therapy*; D007457:Iodine Radioisotopes / Q000627:therapeutic use; D008297:Male; D008959:Models, Neurological; D009368:Neoplasm Transplantation; D011879:Radiotherapy Dosage; D051381:Rats; D011916:Rats, Inbred F344
chemical_list: D007457:Iodine Radioisotopes; D002330:Carmustine