Inclusion Criteria:

- Female patients with histologically confirmed incident invasive breast cancer (T1-4)
with no evidence of regional lymph node metastasis (N0) or distant metastasis (M0)
and after complete primary tumor resection and axillary lymph node dissection less
than 90 days before start of study drug treatment.

- Hormone receptor status is negative

- Patient is premenopausal (spontaneous and regular menses with premenopausal estradiol
levels (>10ng/dL)

- Patient receives adjuvant standard chemotherapy with approved cytotoxic
chemotherapeutic drugs (e.g. AC 4-6 cycles) (prior neoadjuvant CT is allowed)

- Bone density at study entry > -2.5 T-Score

Exclusion Criteria:

- Prior treatment with bisphosphonates and estrogens or treatments for osteoporosis in
addition to calcium and vitamin D

- Severe physical or psychological concomitant diseases and other known concurrent,
severe medical disorder jeopardizing the life of the patient in the immediate future
(e.g., myocardial infarction in previous six months, angina pectoris despite
treatment, uncontrolled severe arterial hypertension, progressive cardiac or
respiratory failure)

- Known hypersensitivity to bisphosphonates

- 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 and recent (within 6 weeks) or planned dental or jaw surgery
(e.g. extraction, implants)