[Strontium-89 for bone metastases from prostate cancer: an update]

Strontium-89 (Sr-89) is a pure emitter with maximum beta energy of 1.46 MeV, average beta energy of 0.58 MeV, and a physical half-life of 50.5 days. It is rapidly taken up by bone and preferentially retained at the sites of osseous metastases. Its biological half-life is >50 days at the metastatic sites, but about 14 days only in the normal bone. The dose of its absorption in the tumor-bearing bone ranges from 21 +/- 4 to 231 +/- 56 cGy/MBq, 2-25 times higher than in the normal bone. Strontium-89 therapy is an effective palliative treatment of bone metastases from prostate cancer, with analgesic effectiveness in 80%.