Painful osteoblastic metastases: the role of nuclear medicine.

Although bone pain from osteoblastic metastases can be ameliorated 50% to 80% of the time by use of intravenously or orally administered radiopharmaceuticals, we cannot accurately predict who will or will not respond. The radiopharmaceuticals containing phosphorus-32, strontium-89 (Metastron), rhenium-186, samarium-153 lexidronam (Quadramet), and tin-117m are effective, but we do not know which of these is the most efficacious or the safest. Toxicity includes mild-to-moderate pancytopenia and an occasional brief flare of pain, and treatment of patients with disseminated intravascular coagulation must be avoided because it may predispose the patient to severe thrombocytopenia. Treatment may be repeated at approximately 8- to 12-week intervals, depending on the time of return to normal leukocytes and platelet counts. Tumoricidal effects are probably not the sole mechanism of pain relief.