A Study of Stereotactic Body Radiation Therapy and Radium (Ra-223) Dichloride in Prostate Cancer That Has Spread to the Bones

Two cycles of Radium (Ra-223) dichloride at 55 kBq/kg or 0.00149 mCi/kg or 1.49 uCi/kg every 4 weeks followed 2-3 weeks later by SBRT at a dose of 9 Gy per fraction for 3 fractions (total dose of 27 Gy) to all sites of radiographically apparent metastatic disease. SBRT fractions can be administered every day or every other day per institutional practice. An additional 4 cycles of Radium (Ra-223) dichloride at 55 kBq/kg or 0.00149 mCi/kg or 1.49 uCi/kg every 4 weeks will then be administered, resuming 2-3 weeks after completion of the final fraction of SBRT.

For both arms, the NaF PET will be used to identify discrete osseous lesions which will become index lesions for the study. The simulation scan (either baseline or after 2 cycles of Ra-223) will be used to generate a suitable SBRT radiation plan, per standard practice. If the index lesions are no longer visible after two cycles of Ra-223, we still intend to consolidate the area with radiation. If the lesions are initially radio-occult on the CT and only visible on the NaF PET, we will fuse the pre-treatment NaF PET/CT to the simulation CT after 2 cycles of Ra-223 to delineate the SBRT treatment volumes.