Strontium-89 Therapy in Painful Bony Metastases

Strontium-89 (Sr), a bone-seeking radiopharmaceutical, has been used successfully in recent trials to palliate bone pain secondary to metastatic disease. The use of this beta emitter in systemic radionuclide therapy should become an integral part in the management of many patients with metastatic disease to the bone. Intravenous Sr may be used in conjunction with standard chemotherapy and external beam radiotherapy. Hematologic toxicity is less than that previously seen with phosphorus-32 e2P), and other side effects are minor. The skeleton is a common site for carcinoma metastases with the most common metastatic sites occurring in the axial skeleton. In order of frequency, the vertebra, proximal femur, pelvis, ribs, sternum, and proximal humerus are most frequently involved. Bone pain secondary to skeletal metastases is the most common intractable cancer pain syndrome (1 ). Bone pain from metastatic disease is usually caused by infiltration and expansion of periosteal membranes by tumor. It may also result from encroachment on hematopoietic tissue in the marrow, compression of the spinal cord or nerve roots and mechanical instability, or pathologic fractures secondary to tumor weakened bones. These are most commonly seen in the proximal femur and cervical and lumbo-sacral spine (2). Metastases to the skeleton occur in ove;r 50% of patients with breast, lung, or prostate cancer, in the later stages of the disease. Pain management becomes a critical issue in these patients. Treatment of metastatic bone pain may initially involve chemo-, surgical, radiation, and hormonal therapies