Despite successful local tumor control, ≈90% of dogs with appendicular osteosarcoma develop metastasis, and pulmonary metastasis is the most common cause of death. Chemotherapy for treatment of metastases has been largely unsuccessful in these patients and is associated with increased toxicity. This study evaluated the feasibility and safety of whole lung irradiation (WLI), an adjuvant technique used in human osteosarcoma patients, to treat dogs with appendicular osteosarcoma. Included in the study were 12 dogs that underwent successful amputation, received 4 doses of carboplatin, and did not have evidence of gross metastasis.
Radiation was delivered via a linear accelerator; 10 daily fractions of 1.75 Gy were administered to each dog for a total of 17.5 Gy. WLI was well tolerated in all dogs. No dogs demonstrated signs of radiation toxicity. The median disease-free interval (376 days) was not significantly longer than in the control group (304.5 days); however, the authors noted WLI may be beneficial in some patients. Larger studies that include adjustments in timing of WLI should be considered.