Response Evaluation of Cancer Therapeutics in Metastatic Castration-Resistant Prostate Cancer to the Bone

This is an observational study and will not influence the choice of treatment. The treating clinicians will be able to use any clinical treatment regimen that is considered appropriated for the patient. This may include hormonal therapy or chemotherapy or therapy with radium-223. In addition, patients may be treated with bisphosphonates/denosumab, and granulocity-colony stimulating factor. The duration of therapy, doses, schedules, timing, premedication, patient monitoring during treatment, dose adjustments, and duration of therapy are entirely at the discretion of the treating clinician.

The use of radiotherapy is permitted, but the details including fields used must be communicated to the reporting radiologist to ensure this does not affect the interpretation of imaging. All other supportive or palliative treatments are permitted.

All patients will undergo imaging assessments as follows:

* At baseline, CT, BS (99mTc-MDP) and Whole Body-Magnetic Resonance Imaging (WB-MRI) will be performed. * Follow-up imaging will be CT, BS and WB-MRI performed every 12 weeks until week 96, and then every 24 weeks until disease progression occurs or week 192.

Additional patient assessments to be performed include:

* questionnaires at baseline, week 36 and end of study to evaluate patient perception, acceptance and preferences regarding the imaging modalities. * clinical and physical examinations according to routine clinical practice. The radiologist reporting the WB-MRI will be blinded to the results of the CT and BS.

The radiologist reporting the CT and the nuclear medicine physician reporting the BS will likewise be blinded to the results of the WB-MRI.

Neither treating clinicians nor patients will be blinded at any point.