Efficacy and Complications of Samarium153-EDTMP Added to Palliative Local Radiotherapy for Bone Metastases

This study was designed to evaluate the efficacy and complications of the bone seeking radiopharmaceutical Samarium 153 added to local external beam radiotherapy (EBRT) for pain palliation in patients with metastatic bone pain. Patients with multiple bone metastases and an estimated life expectancy of more than 3 months were eligible for this study, provided that they had a dominant localized pain for which palliative EBRT with local fields had been planned. Treatment was intravenous injection of 1.5 mCi (56 MBq)/kg of 153Sm-EDTMP, and local radiotherapy with 30 Gy in 10 fractions. Pain scoring was performed by the Farsi (Persian) version of Brief Pain Inventory (BPI), and response was categorized according to the International Consensus on Bone Metastases guidelines. Twenty-six patients (10 male, 16 female,) aged 30-80 years (mean 55 years) were enrolled in the study. Primary cancers were 15 breast, 7 prostate, and 4 others. Of the enrolled patients, 23 received the full treatment and were available for pain response evaluation. In these patients, overall response was 90% and there was 10% no response. 30% of the patients had a significant response with their pain score reducing to more than half. One patient (4.3%) experienced grade 3 leucopenia, and 1 patient grade 3 thrombocytopenia. All other patients experienced grade 0-2 of bone marrow toxicity. 153Sm-EDTMP adjuvant to local radiotherapy resulted in higher overall response compared to the results of our studies on EBRT alone and Samarium alone in similar populations of patients, and to the results in literature. Samarium 153 did not significantly add the complications of radiotherapy alone.