Palliative therapy for metastatic bone pain with 153 S M-EDTMP

Samarium-153 ethylenediamine-tetra methylene phosphonate (153 Sm-EDTMP) has been proposed as a radionuclide therapeutic agent to palliate pain resulting from osteoblastic metastatic bone cancer. Six patients with disseminated skeletal metastases from a variety of tumor types underwent clinical trial of this agent obtained from the Office of Atomic Energy for Peace (OAEP), Thailand. All of the patients received 1 mCi/kg of 153 Sm-EDTMP intravenously. The preferential localization of 153 Sm-EDTMP in bony lesions was assessed and compared to the routine bone seeking agent, 99mTc-MDP. Both radiopharmaceuticals showed similar uptake in lesional and nonlesional bone (p < 0.001). The retained skeletal activity varied from 56.54% to 76.23% of the administered dose and greater than 91% ± 6.77% of the non osseous activity was cleared in the urine within 6 hours in all patients. Fifty percents of the patients developed a transient exacerbation of their pre-153 Sm-EDTMP pain and lasted within 1-2 weeks. The other patients lost follow up. This study indicates potential for 153 Sm-EDTMP as a therapeutic radiopharmaceutical for pain palliation of cancer bone metastases