Internal radionuclide therapy of primary osteosarcoma in dogs, using Sm-153-ethylene-diamino-tetramethylenephosphonate (EDTMP)

Fifteen dogs were referred because of a spontaneous bone tumor, lameness, a nd local pain. The osteosarcoma diagnosis was established by clinical exami nation, X-ray, bone scintigraphy, and histological examination of biopsy ma terial. The tumors were located in the extremities (n = 12), scapula (n = 1 ), maxilla (n = 1), and the frontal bone (n = 1). The dogs were given one t o four i.v. injections of Sm-153-labeled ethylene-diamino-tetramethylene-ph osphonate (Sm-153-EDTMP; 36-57 MBq/kg body weight). Three dogs had surgery in addition to the radionuclide treatment, Platelet and WBC counts showed a moderate and transient decrease. No other toxicity was observed. Average t umor doses after a single injection were similar to 20 Gy, considerably hig her in some areas because of inhomogeneous uptake. Macroscopically distant metastases were detected in seven dogs at autopsy. One dog died from an int ercurrent disease, free of cancer, 5 months after the radionuclide treatmen t. None of the dogs was cured. The median and mean survival times from the first treatment to death or euthanasia were 150 and 252 days, respectively. Nine of the dogs had obvious pain relief, and five of them seemed pain-fre e: one for 20 months and one for 48 months. It is concluded that high tumor doses may be deposited in dog osteosarcomas by Sm-153-EDTMP, and the ratio between tumor dose and the dose to surrounding tissues is favorable. The t reatment gives pain relief and in some cases tumor growth delay. In combina tion with surgery, Sm-153-EDTMP may prolong life significantly and possibly cure the disease because the development of metastases are seemingly postp oned. No serious side effects were observed.