Project plan changed, study conduct was no longer needed.

There are no real-world data that describes how Radium-223 (Ra-223) is being used in combination with abiraterone/enzalutamide (abi/enza) 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 abi/enza 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 abi/enza. 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 abi/enza in first line treatment.

Inclusion Criteria:

• Diagnosis of mCRPC and bone metastases
• ≥ 40 years of age at diagnosis of mCRPC
• Initiated first line treatment for mCRPC with abi/enza (use of sipuleucel-T prior to initiation of abi or enza is allowed)
• Receipt of at least one cycle of radium-223 after 15 May 2013
• First cycle of Ra-223 occurs while receiving first line treatment with abi/enza
• Treated with abi/enza for at least 28 days (1 cycle) following initiation of Ra-223
• Initiation of Ra-223 at least 6 months after the start of treatment with abi/enza
• Completion of Ra-223 treatment prior to the receipt of any chemotherapy for mCRPC
• At least 12 months of follow-up (or until death) from date of initiation of Ra-223
• Known date of death (if patient deceased)

Exclusion Criteria:

• Receipt of any prior chemotherapy during hormone sensitive disease or any time before mCPRC
• Active participant in an interventional clinical trial for CRPC in first line
• Presence of visceral metastases at initiation of Ra-223 treatment
• Treated with abi/enza (with or without docetaxel) prior to the development of metastatic and/or castration resistant disease

Patients will be identified by their treating physicians (oncologists and urologists), who will be recruited for participation in the research from the Cardinal Health Oncology Research Network (CHORN).