 There are no real-world data that describes how Radium-223 Ra-223 is being used in combination with abirateroneenzalutamide abienza or evidence describing outcomes of this combination usage for the treatment of metastatic castration resistant prostate cancer mCRPC. To address these data gaps a cohort of mCRPC patients will be chosen who received Ra-223 concomitant with abienza in first line therapy to assess the treatment patterns following first line and clinical outcomes from initiation of first line treatment. For the purpose of this study concomitant use will be defined as Ra-223 initiated after at least 6 months from the start of first line abienza. The specific objectives of the study are to describe the outcomes, treatment patterns, patient and provider characteristics of mCRPC patients treated with Ra-223 concomittantly with abienza in first line treatment. 