Introduction

Recent attempts to improve the long-term prognosis for canine osteosarcoma with intensified chemotherapy regimens have largely been unsuccessful. Whole lung irradiation (WLI) has been used successfully in humans as an adjuvant treatment for osteosarcoma. The aim of this study is to describe the safety and feasibility of WLI in dogs with appendicular osteosarcoma. Our hypothesis is that WLI as an adjuvant to standard of care treatment will be safe and well tolerated.

Methods

Twelve client-owned dogs with appendicular osteosarcoma were enrolled in this prospective clinical trial. Dogs were included if they had completed amputation and 4 doses of carboplatin without radiographic evidence of metastasis. Ten once-daily fractions of 1.75 Gray were administered to 100% of the lung volume, beginning 3 weeks after the last dose of carboplatin. Dogs were monitored with physical examinations and chest radiographs every 8 weeks after WLI.

Results

The most common side effect during radiation therapy was weight loss (n=8), with an average loss of 4% body weight per dog. Hematologic toxicity occurred in 6 dogs and was low grade in all cases. No dogs developed overt pneumonitis. The median follow-up time following radiation therapy was 20 weeks. No dogs experienced late side effects attributable to radiation therapy. No pathologic changes were identified on thoracic radiographs prior to disease progression in any dog.

Conclusion

WLI appears to be safe and well tolerated in dogs. This protocol warrants further investigation for toxicity characterization and efficacy evaluation with a larger scale clinical trial.

Funding Information

GINN Grant (Internal funding through Texas A&M)
ACVIM Resident Research Grant
Katherine and Rebecca Rochelle Chair in Oncology