Inclusion Criteria:

- ≥ 30 years of age

- has histologically or cytologically confirmed breast or prostate carcinoma

- presents with bony metastases, confirmed by scintigraphic imaging within the previous
4 weeks

- relapsing with new foci in the skeleton after previous external radiotherapy

- has a life expectancy of at least 8 weeks (study part Ia), 5 months for study part Ib

- good performance status; ECOG (Eastern Cooperative Oncology Group) status 0-2

- has normal bone marrow, hepatic, renal and cardiac functions

- clinical chemical laboratory values are within pre-specified range, measured within 7
days prior to dosing day

- for female patients: post-menopausal, surgically sterile or taking adequate
contraceptive precaution

Exclusion Criteria:

- has previously been included in this study. This criterion is applicable for patients
that receive a single injection of the study drug, but not for patients to be
re-treated, or for those to receive a fractionated dosing regimen (study part Ib).

- has received an investigational drug in the 4 weeks before or is scheduled to
receiving one during or in the 8 weeks after study drug administration. This
criterion is applicable for patients that receive a single injection of the study
drug and for patients to be re-treated.

- has received any other investigational drug than radium-223 in the 4 weeks before
first injection of study drug or is scheduled to receiving one during or in the 8
weeks after the fractionated study drug regimen. This criterion is applicable for
patients receiving fractionated dose of the study drug.

- has received chemo-, immuno-, or radiotherapy within the last 4 weeks prior to entry
in the study

- has other active, serious, life-threatening disease with a life expectancy of less
than 8 weeks

- has any uncontrolled infection

- requires oxygen for pulmonary metastases

- has poor renal function with S-Creatinine >150 mmol/L (males), >100 mmol/L (females)

- has heart insufficiency, Class III or IV NYHA (New York Heart Association)

- is pregnant or lactating

- for female patients: of childbearing potential, and not taking adequate contraceptive
measures