This study is aimed to compare whole body MRI (WB-MRI) with Bone Scintigraphy (BS) and Computerized Tomography (CT) scans in patients receiving treatment for metastatic castration-resistant prostate cancer to the bone.

This is a monocentric, prospective observational study.

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.

Inclusion Criteria:

• Histological diagnosis of castration-resistant prostate cancer,
• Single or multiple bone metastases,
• Life expectancy of over 6 months,
• No current active malignancy other than prostate cancer,
• Provision of written informed consent.

Exclusion Criteria:

• Absolute contraindication to WB-MRI, CT or BS,
• Radical treatment of sole site of metastatic disease (e.g. Cyberknife to solitary metastatic lesion),
• Psychological, familial, sociological or geographical conditions that would hamper compliance with the study protocol; such conditions are to be discussed with the patient as part of the informed consent process.

The estimated rate of recruitment to the study 6-7 patients a month, thus it is expected that patient accrual will be completed within 7 months.

Based on recent treatment patterns, the expected distribution of treatments is:

• Hormonal treatments

  • Enzalutamide: 14 patients
  • Abiraterone: 8 patients

• Chemotherapy

  • Docetaxel: 11 patients
  • Cabazitaxel: 5 patients

• Radiopharmaceutical drug - Radium-223: 2 patients