This open non-randomized, single-arm, multicenter, observational study is designed to evaluate the correlation between bone turnover markers and the response to treatment in patients with breast cancer and bone metastases. In this observational study, ibandronate (Bondronat) will be prescribed and used in accordance with the standards of care. Data will be collected for 12 months.

Inclusion Criteria:

• All criteria in accordance with the Summary of Product Characteristics of Bondronat (ibandronate)
• Adult patients greater than (>) 18 years of age
• Histologically confirmed breast cancer
• Confirmed bone metastasis (by bone scintigraphy, X-ray, computed tomography or magnetic resonance imaging)
• Life expectancy >6 months
• No previous bisphosphonate therapy
• Patients signed written informed consent form before study start

Exclusion Criteria:

• All criteria in accordance with the Summary of Product Characteristics of Bondronat(ibandronate)
• Hypersensitivity to the active substance or any of the excipients of Bondronat (ibandronate)
• Hypersensitivity to bisphosphonates

Patients with breast cancer and bone metastases who have been prescribed ibandronate (Bondronat) will be evaluated in the routine oncological setting for 12 months.