The purpose of this study is to evaluate the use of an oral bisphosphonate (alendronate) in preventing bone loss in postmenopausal women with early breast cancer who are receiving anastrozole therapy, and to determine how long alendronate treatment is needed.

Inclusion Criteria:

• Postmenopausal
• Adequately diagnosed and treated Stage I-IIIa early breast cancer
• Oestrogen receptor and/or progesterone receptor positive breast cancer
• Eastern Cooperative Oncology Group (ECOG) performance status less than or equal to 2
• Hormone replacement therapy (HRT) must be discontinued at least 2 weeks prior to registration
• Any prior tamoxifen taken for a total of 8 weeks or less
• Any prior anastrozole taken for a total of 4 weeks or less
• Anastrozole is clinically indicated to be the best adjuvant strategy
• Signed written informed consent

Exclusion Criteria:

• Clinical or radiological evidence of distant spread of disease
• Prior treatment with bisphosphonates within the past 12 months
• Prior treatment with continuous systemic corticosteroids within the past 12 months
• Prior use of parathyroid hormone for more than 1 week
• Prior use of systemic sodium fluoride for > 3 months during the past 2 years
• Currently treated with any drugs known to affect the skeleton
• Abnormal renal function (serum creatinine greater than or equal to 265.2 mmol/L)
• History of diseases with influence on bone metabolism. Patients with lactose intolerance are also excluded
• Delayed oesophageal emptying such as stricture or achalasia
• Hypersensitivity to alendronate or anastrozole
• Previous or concomitant malignancy within the past 5 years EXCEPT adequately treated basal or squamous cell carcinoma of the skin or in situ carcinoma of the cervix
• AST/SGOT and/or ALT/SGPT > 3 x ULN in combination with other laboratory and clinical abnormalities indicating liver insufficiency
• Fracture due to minimal trauma, demonstrated radiologically