Radium-223 as an Approved Modality for Treatment of Bone Metastases

Radium-223 dichloride (²²³Ra) is an α-emitter radionuclide approved for treatment of osteoblastic metastases in castrate-resistant prostate cancer (mCRPC) patients. ²²³Ra increases overall survival, improves bone pain, increases the median time to the first skeletal-related event, reduces the use of external beam radiation therapy for bone pain palliation, reduces the rates of spinal cord compression, and hospitalization. ²²³Ra therapy has minimal side effects; the most common hematological side effects are anemia, thrombocytopenia and neutropenia while the nonhematological side effects that may occur are bone pain flare, nausea, fatigue, and diarrhea. Alongside ²²³Ra therapy there are currently a variety of first-line therapeutic options available to treat mCRPC patients and much debate regarding the appropriate treatment algorithm for these patients and the possible combination of therapies among the ones available. In this article, we review the rationale behind ²²³Ra therapy as well as ²²³Ra mechanisms of action, biodistribution and dosimetry, optimal timing possibilities to initiate ²²³Ra in contrast to other treatments available, the association of ²²³Ra with other therapies and the means of evaluating patients in order to properly deliver to ²²³Ra therapy. Furthermore, we will discuss ²²³Ra dose administration possibilities, patient and dose preparation and the challenges of treatment response evaluation during and after ²²³Ra.