An overview of current clinical experience with strontium-89 (Metastron).

Prostate cancer is one of the most common tumors in men. At presentation, 50% of patients have advanced disease and 25% have bone metastases. Hormonal palliation is the treatment of choice for metastatic bone pain, with a pain-free response rate of 75% for a period of 16-18 months. Second-line treatment with chemotherapy has a moderate and short-term effect. Once endocrine therapy and chemotherapy cease to be effective, radiotherapy is a good option for recurrent painful bone metastases. Diffuse painful metastases can be treated with half-body irradiation with a response rate of up to 70%, but there is considerable toxicity. Strontium-89 (Metastron) is a calcium analog radionuclide that is selectively absorbed at bone locations with increased osteoblastic activity. It is a pure beta-emitter with bone penetration of 0.8 cm, and it has been used in multiple trials with response rates of up to 80%. Results are reported with Metastron in 28 patients with diffuse painful bone metastases, in whom a response rate of 82% was seen.