Inclusion Criteria

• Female patients with histologically confirmed incident invasive breast cancer (T1-4) with positive hormone receptor status (ER and/or PgR positive) and no evidence of regional lymph node metastasis (N0) or distant metastasis (M0)
• Patient has undergone complete primary tumor resection and axillary lymph node dissection less than 90 days before start of study drug treatment.
• Patient is premenopausal at diagnosis of breast cancer (spontaneous and regular menses with premenopausal estradiol levels (>10 ng/dL)
• Patient receives adjuvant standard chemoendocrine or endocrine therapy
• Bone density at study entry > -2.5 T-Score

Exclusion Criteria

• History of treatment or disease affecting bone metabolism (e.g., Paget's disease, primary hyperparathyroidism), prior treatment with bisphosphonates or treatments for osteoporosis in addition to calcium and vitamin D
• Abnormal renal function
• Current active dental problems including infection of the teeth or jawbone (maxilla or mandibular); dental or fixture trauma, or a current or prior diagnosis of osteonecrosis of the jaw (ONJ), of exposed bone in the mouth, or of slow healing after dental procedures, recent (within 6 weeks) or planned dental or jaw surgery (e.g. extraction, implants)
• Pregnancy or lactation
• Women of childbearing potential not applying a medically recognized form of contraception (i.e., oral contraceptives or implants, IUD, vaginal diaphragm or sponge, or condom with spermicide)

Other protocol-defined inclusion/exclusion criteria may apply