title: Orthotopic model of canine osteosarcoma in athymic rats for evaluation of stereotactic radiotherapy.
abstract: OBJECTIVE
  To develop an orthotopic model of canine osteosarcoma in athymic rats as a model for evaluating the effects of stereotactic radiotherapy (SRT) on osteosarcoma cells.
  
  
  METHODS
  26 athymic nude rats.
  
  
  METHODS
  3 experiments were performed. In the first 2 experiments, rats were injected with 1 × 10(6) Abrams canine osteosarcoma cells into the proximal aspect of the tibia (n = 12) or distal aspect of the femur (6). Tumor engraftment and progression were monitored weekly via radiography, luciferase imaging, and measurement of urine pyridinoline concentration for 5 weeks and histologic evaluation after euthanasia. In the third experiment, 8 rats underwent canine osteosarcoma cell injection into the distal aspect of the femur and SRT was administered to the affected area in three 12-Gy fractions delivered on consecutive days (total radiation dose, 36 Gy). Percentage tumor necrosis and urinary pyridinoline concentrations were used to assess local tumor control. The short-term effect of SRT on skin was also evaluated.
  
  
  RESULTS
  Tumors developed in 10 of 12 tibial sites and all 14 femoral sites. Administration of SRT to rats with femoral osteosarcoma was feasible and successful. Mean tumor necrosis of 95% was achieved histologically, and minimal adverse skin effects were observed.
  
  
  CONCLUSIONS
  The orthotopic model of canine osteosarcoma in rats developed in this study was suitable for evaluating the effects of local tumor control and can be used in future studies to evaluate optimization of SRT duration, dose, and fractionation schemes. The model could also allow evaluation of other treatments in combination with SRT, such as chemotherapy or bisphosphonate, radioprotectant, or parathyroid hormone treatment.
authors: Department of Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO 80523, USA.
authors: Anthony L
authors: AL
authors: Schwartz
authors: James T
authors: JT
authors: Custis
authors: Joseph F
authors: JF
authors: Harmon
authors: Barbara E
authors: BE
authors: Powers
authors: Laura S
authors: LS
authors: Chubb
authors: Susan M
authors: SM
authors: LaRue
authors: Nicole P
authors: NP
authors: Ehrhart
authors: Stewart D
authors: SD
authors: Ryan
mesh_terms: D000818:Animals; D001859:Bone Neoplasms / Q000473:pathology / Q000601:surgery / Q000662:veterinary*; D004283:Dog Diseases / Q000473:pathology* / Q000601:surgery*; D004285:Dogs; D005269:Femur / Q000473:pathology / Q000601:surgery; D006651:Histocytochemistry / Q000662:veterinary; D009368:Neoplasm Transplantation; D012516:Osteosarcoma / Q000473:pathology / Q000601:surgery / Q000662:veterinary*; D016634:Radiosurgery / Q000379:methods / Q000592:standards / Q000662:veterinary*; D051381:Rats; D011923:Rats, Nude; D013977:Tibia / Q000473:pathology / Q000601:surgery; D014183:Transplantation, Heterologous