The objective of the study is to investigate whether blood markers can be used to predict the development of bone metastases and to assess the efficacy and safety of zoledronic acid in cancer treatment induced bone loss.

Inclusion Criteria:

• All stages of prostate cancer without bone metastases
• No evidence of severe osteoporosis
• ECOG performance status 0, 1 or 2

Exclusion Criteria:

• Surgery / fracture at the lumbosacral spine, bilateral hip implants
• Evidence of metabolic bone diseases,
• Treatment with bisphosphonates or calcitonin within the previous year or chronic systemic corticosteroid treatment
• Abnormal kidney or liver function
• Other cancers within the last 5 years

Other protocol-defined exclusion criteria may apply.