Effectiveness of Zoledronic Acid in the Prevention of Osteoporosis in Early Breast Cancer Patients Receiving Letrozole

Inclusion Criteria:

• Postmenopausal women with histologically documented early (non-metastatic) breastcancer

• Previous treatment with tamoxifen for at least 2.5 years and not more than 3.5 years

• Assigned to receive letrozole treatment

• Karnofsky performance status ≥ 70

• Life expectancy ≥ 16 weeks

• Signed informed consent after full explanation of study by participating clinician andprio to any study specific procedures

• Adjuvant or neoadjuvant chemotherapy is allowed

• No clinical and/or radiologic evidence of distant metastases

• No prior treatment with an aromatase inhibitor

• Able to comply with treatment and scheduled follow-up visits

• Age between 18 and 82 years

Exclusion Criteria:

• Pregnant or lactating women or women with child bearing potential

• Patients with other malignancies except except adequately treated basal cell carcinomaof the skin or in-situ cervix carcinoma

• Active infection or other serious underlying medical condition which would impair theability of the patient to receive protocol treatment

• Clinical and/or radiological evidence of distant metastases.

• Evidence of pathological fracture

• Prior treatment with an aromatase inhibitor

• Prior administration of any intravenous bisphosphonate during the last year.

• Oral bisphosphonate must be discontinued within 4 weeks of enrollment

• Administration of long-term systemic corticosteroids within the last 12 months (shortterm steroid treatment is allowed.)

• Prior use of parathyroid hormone treatment for more than 1 week

• Use of any drug known to affect the skeleton (calcitonin, mithramycin, galliumnitrate) within two weeks prior to enrollment

• Abnormal renal function: creatinine clearance must be above 30 ml/min (calculated byCockroft formula)

• Evidence of metabolic bone disease( Paget's, osteogenesis imperfecta,hyperparathyroidism within the 12 months prior to enrollment)

• Baseline lumbar spine and or total hip Bone Mineral Density T score below -2

• Known hypersensitivity to zoledronic acid

• Psychological, familial, sociologic, or geographic conditions which do not permitmedical follow-up and compliance with the study protocol

• White blood cell ≤ 3.0 x 10exp9 /L or granulocytes ≤ 1.5 x 10exp9/L or platelets ≤100x 10exp9

• Total bilirubin> 1.5 x upper normal limit, SGOT and SGPT > 2.5 x upper normal limit

• Unable to undergo DXA bone density scanning (spine deformity, severe scoliosis, lumbarsacral spine surgery)