Respuesta analgésica y efectos secundarios en pacientes con metástasis osteoblásticas tratados con samario-153 etilendiaminotetrametilenfosfato / Samarium 153 EDTMP in the treatment of metastatic bone pain: evaluation of analgesic response and secondary effects

RESUMO

Background: Samarium153 EDTMP, a beta and gamma emitter, is used in the palliative therapy of painful bone metastases. Aim: To evaluate the analgesic effects and myelotoxicity of Samarium153 EDTMP in patients with prostate, breast and renal carcinoma. Patients and methods: Twenty patients with bone metastases (11 males), aged 65 years old as a mean, received a 1 to 2 mCi/kg intravenous dose of Samarium153 EDTMP, produced in Chile. Patients were followed thereafter during 4 to 40 weeks. Pain was assessed using a visual analogue scale. Results: Pain decreased from a score of 6.4 prior to treatment, to 2.7 at the fourth week of therapy and the effect lasted a mean of 12.5 weeks. Myelotoxicity was observed in 68percent of cases (WHO stage I in 21 percent, stage II in 37 percent, stage III in 11percent and no patients in stage IV). Platelets were the most affected series and neutrophils the least affected. Cell counts returned to normal between the sixth and eighth week. Seventy nine percent of patients decreased their basal analgesic therapy at the sixth week and 88percent did so at the eighth week. Forty one percent of these patients discontinued all analgesics. Conclusions: Samarium153 EDTMP is effective in the treatment of pain in patients with bone metastases and its myelotoxicity is low to moderate. It should be considered as a therapy for this type of pain, with the precaution of performing periodical bood counts