SAMARIUM(153) EDTMP IN THE TREATMENT OF METASTATIC BONE PAIN - EVALUATION OF ANALGESIC RESPONSE AND SECONDARY EFFECTS

Background: Samarium(153) EDTMP, a beta and gamma emitter, is used in the palliative therapy of painful bone metastases. Aim: To evaluate th e analgesic effects and myelotoxicity of Samraium(153) EDTMP in patien ts wit prostate, breast and renal carcinoma. Patients and methods: Twe nty patients with bone metastases (11 males), aged 65 years old as a m ean, received a 1 to 2 mCi/kg intravenous dose of Samarium(153) EDTMP, produced in Chile. Patients were followed thereafter during 4 to 40 w eeks. Pain was assessed using a visual analogue scale. Results: Pain d ecreased from a score of 6.4 prior to treatment, to 2.7 at the fourth week of therapy and th effect lasted a mean of 12.5 weeks. Myelotoxici ty was observed in 68% of cases (WHO stage I in 21%, stage II in 37%, stage III in 11% and no patients in stage IV). Platelets were th most affected series and neutrophils the least affected. Cell counts return ed to normal between the sixth and eighth week. Seventy nine percent o f patients decreased their basal analgesic therapy at the sixth week a nd 88% did so at the eighth week. Forty one percent of these patients discontinued all analgesics. Conclusions: Samarium(153) EDTMP is effec tive in the treatment of pain in patients with bone metastases and its myelotoxicity is low to moderate. It should be considered as a therap y for this type of pain, with the precaution of performing periodical bood counts.