Systemic radiopharmaceutical therapy of painful osteoblastic metastases

Bone pain from osteoblastic metastases can be ameliorated 40% to 80% of the time. Although we can predict nonresponders, we cannot predict responders; however, patients with a better performance scale may have a better chance of pain relief. Radiopharmaceuticals containing phosphorus 32, strontium 89, samarium 153, rhenium 186, and tin 117m are effective, but we do not know which is the most efficacious and the safest. Toxicity includes the flare phenomenon and mild to moderate pancytopenia, but disseminated intravascular coagulation can cause severe, life-threatening thrombocytopenia. This treatment may be repeated at about 9- to 12-week intervals, perhaps earlier with (153)Sm lexidronam, (186)Re etidronate, and (117m)Sn pentetate, with a success rate approaching that of the initial injection. The duration of action of pain reduction ranges from 2 weeks to many months. Tumorical effects are probably not the only mechanism of pain relief.