Clinical and clinicopathologic response of canine bone tumor patients to treatment with samarium-153-EDTMP

Forty dogs with spontaneous skeletal neoplasia were treated with 153Sm-EDTMP (ethylenediaminetetramethylene phosphonic acid). Both primary and metastatic lesions were treated. Two treatment regimes, a single (37 MBq (1.0 mCi)/kg dose or two 37 MBq (1.0 mCi)/kg doses separated by 1 wk) were tested. Response to treatment was varied. Large lesions with minimal tumor bone formation responded poorly, while primary lesions with substantial ossification usually exhibited a transient response. Small lesions with minimal lysis, metastatic lesions, and axial skeleton lesions generally responded well. The major adverse side effects of treatment were platelet and white blood cell count depression below baseline values for up to 4 wk (p less than 0.05). Minor depression of packed cell volume and transient elevation of serum alkaline phosphatase were also noted (p less than 0.05). No significant differences (p greater than 0.05) between the two treatment groups, either in treatment effect or undesirable side effects, were detected.