Bone Therapies

The following molecular radiotherapies are currently used to relieve pain and/or treat castration-resistant prostate cancer that has spread to the bone:

strontium-89 chloride (Metastron®)
samarium-153 (Quadramet®)
radium-223 dichloride (Xofigo®)

Both strontium-89 and radium-223 are radionuclides that target areas of increased bone turnover, and are directly injected into the bloodstream. Samarium-153 must be combined with a molecule that targets bone prior to injection into the bloodstream. Often men receiving a course of targeted radionuclide radiotherapy therapy receive several injections, each one separated from the others by a period of weeks. Research has shown that this is effective in relieving pain. Side effects of the therapy include myelosuppression, or a decrease in the production of red blood cells, white blood cells and platelets. Radionuclide treatment is sometimes combined with chemotherapy. Radium-223 (Xofigo), the newest radiopharmaceutical to be approved by the United States Food and Drug Administration, is unique because of the type of radiation it emits. Unlike strontium-89 and samarium-153 that emit beta particles, radium-223 emits alpha particles. Alpha particles deposit a higher amount of energy over a shorter distance than beta particles. Xofigo is especially promising because in addition to providing pain palliation, studies of Xofigo have shown that it can also extend overall survival in patients.