Radium-223-dichloride is approved therapy for patients with metastatic castration-resistant prostate cancer and bone metastases. More than 20 % of patients treated at Rigshospitalet develop bone marrow suppression as a side effect to Radium therapy The aim of the study is to examine biomarkers of bone marrow suppression and recovery during Radium therapy as well as markers of bone remodeling.

Radium-223-dichloride is approved therapy for patients with metastatic castration-resistant prostate cancer and bone metastases. Therapy is administered intravenously every 4 weeks for up to 6 cycles. More than 20 % of patients treated at Rigshospitalet develop bone marrow suppression as a side effect to Radium therapy, which delays or excludes the patient from further oncological therapy. Especially thrombocytopenia is a frequent side-effect and can be long lasting.

The aim of the study is to examine whether biomarkers of bone marrow recovery (immature platelets, platelet volume, reticulocytes, red cell distribution width) can predict development of hematological toxicity during Radium therapy. Furthermore, to investigate whether these biomarkers can predict recovery from toxicity in patients who develop bone marrow suppression during therapy.

A secondary aim of the study is to evaluate whether dynamics in biomarkers of bone remodeling during Radium therapy is correlated to overall survival and time to symptomatic skeletal event. Optimally these biomarkers can aid in monitoring therapy.

Inclusion Criteria:

• Metastatic castration resistant prostate cancer
• Planned to initiate Radium therapy
• Age > 18 years
• Able to understand study protocol and give informed consent

Exclusion Criteria:

• None

Patients with metastatic castration-resistant prostate cancer, who initiate therapy with Radium-223 at Rigshospitalet, Copenhagen, Denmark