Rhenium-188-HEDP vs. Radium-223-chloride in Patients With Advanced Prostate Cancer Refractory to Hormonal Therapy

Inclusion Criteria: * Male, 18 years or older * Histologically confirmed prostate cancer * Bone metastases (≥ 6 lesions) showing pathological uptake at bone scintigraphy. * WHO performance status of ≤2 * Life expectancy of at least 6 months * Castration-resistant disease: serum testosterone level of ≤ 1.7 nmol per liter (≤50 ng per deciliter) after bilateral orchiectomy or during maintenance treatment consisting of androgen-ablation therapy with a luteinizing hormone-releasing hormone agonist. During study treatment the maintenance androgen-deprivation therapy must be continued. * Baseline PSA ≥5 ng/ml with evidence of progressively increasing PSA values * Symptomatic disease with either regular use of analgesic medication or treatment with external-beam radiotherapy for cancer-related bone pain within the previous 12 weeks. * Progression on or after treatment with docetaxel, or inability to receive docetaxel. * Adequate renal function (serum creatinine level ≤1.5 x ULN) * Adequate hematological function defined as absolute neutrophil count ≥ 1.5x10\^9/L and platelet count ≥100x 10\^9/L) * Written informed consent Exclusion Criteria: * Treatment with chemotherapy within the previous 4 weeks * Continuation of treatment with abiraterone or enzalutamide * Previous hemibody external radiotherapy * Systemic radiotherapy with radioisotopes within the previous 24 weeks * Malignant lymphadenopathy ≥3cm in the short-axis diameter * Presence of visceral metastases * Imminent of established spinal cord compression * Active uncontrolled bacterial, viral or fungal infection * History of another malignancy within the last five years except adequately treated basal cell carcinoma of the skin * Organ allografts requiring immunosuppressive therapy. * Any serious uncontrolled concommitant disease * Any psychological, familial, sociological or geographical condition potentially hampering compliance with the study protocol and follow-up schedule: those conditions should be discussed with the patient before registration in the trial.