Radionuclide therapy for palliation of pain due to osteoblastic metastases.

Beta-emitting, bone-seeking radiopharmaceuticals, administered systemically, represent a good alternative or adjuvant to external beam radiotherapy for palliation of painful osteoblastic bone metastases. The most frequently used radiopharmaceutical for this purpose is strontium 89, followed by samarium 153 ethylenediaminetetramethylene phosphonate, and infrequently phosphorus 32 orthophosphate. Prior to consideration for radionuclide therapy, recent bone scans should be evaluated in order to determine if the patient has painful osteoblastic lesions likely to respond to therapy. Approximately 70% of patients with prostate and breast cancer will have a reduction in pain in response to radionuclide therapy, beginning within 2 to 4 weeks and lasting between 2 and 6 months. Patients who are expected to live 3 or more months are more likely to benefit than patients with shorter duration life expectancy. Hematosuppression is the chief side effect of radionuclide therapy, with leukopenia and thrombocytopenia more likely to be clinically significant than anemia. Relative contraindications for treatment include osteolytic lesions, pending spinal cord compression or pathologic fracture, preexisting severe myelosuppression, urinary incontinence, inability to follow radiation safety precautions, and severe renal insufficiency.