Study of Zoledronic Acid Administered Monthly Versus Every 3 Months in Multiple Myeloma and Breast Cancer Patients Who Were Treated With Zoledronic Acid the Prior Year

Inclusion Criteria: * Male or female between 18-75 years of age * Multiple myeloma or breast cancer with bone involvement * Treatment with zoledronic acid for bone lesions between 10-15 months prior to entry into study with a total of 9-20 infusions received. Exclusion Criteria: * Current active dental problems or recent (within 8 weeks) or planned dental or jaw surgery * Active or uncontrolled infection, liver, or renal disease * History of treatment with intravenous bisphosphonates * Diagnosis of metabolic bone disorders other than osteoporosis (e.g. Paget's disease) Other protocol-defined inclusion/exclusion criteria may apply.