Resection of pulmonary metastases in canine osteosarcoma: 36 cases (1983-1992).

Thirty-six dogs underwent pulmonary metastatectomy for osteosarcoma. All patients had been treated for histologically confirmed osteosarcoma of the appendicular skeleton. Treatment for the primary tumor consisted of amputation or a limb sparing procedure in conjunction with adjuvant chemotherapy, local radiation therapy, or both. Significant factors in determining prognosis included the disease-free interval (DFI) between treatment of the primary tumor and development of pulmonary metastases and the number of metastatic nodules present at surgery. Dogs that developed pulmonary metastases 300 days or more after diagnosis of the primary tumor had a median DFI of 128 days after metastatectomy. Dogs that developed pulmonary metastases fewer than 300 days after diagnosis had a median DFI of 58 days. Dogs with one or two metastatic nodules removed had a median DFI of 95 days, whereas dogs with three or more nodules removed had a median DFI of 53 days. The results of this study indicate that prognostic variables exist for dogs with metastatic pulmonary osteosarcoma and can help predict survival after metastatectomy. These variables are similar to the prognostic variables that have been determined for human patients undergoing pulmonary metastatectomy because of osteosarcoma. Though a controversial procedure, pulmonary metastatectomy seems to be a valid treatment option for selected dogs with metastatic pulmonary osteosarcoma.