Zoledronate in Preventing Bone Loss in Postmenopausal Women Who Are Receiving Letrozole for Stage I, Stage II, or Stage IIIA Breast Cancer

DISEASE CHARACTERISTICS:

* Diagnosis of breast cancer

  * Stage I, II, or IIIA disease
* Completed ≤ 6 years of adjuvant tamoxifen therapy
* Total baseline lumbar spine or femoral neck bone mineral density T-score below -2.0 standard deviation (e.g., a patient with a T-score of -2.1 in ineligible; a patient with a T-score of -1.9 is eligible)
* No clinical or radiological evidence of recurrent or metastatic disease
* Hormone receptor status:

  * Estrogen receptor- and/or progesterone receptor-positive

PATIENT CHARACTERISTICS:

Age

* Postmenopausal

Sex

* Female

Menopausal status

* Postmenopausal, defined by 1 of the following:

  * Over 55 years of age with cessation of menses
  * 55 years of age and under with spontaneous cessation of menses for \> 1 year
  * 55 years of age and under with spontaneous cessation of menses for ≤ 1 year, but amenorrheic (e.g., spontaneous or secondary to hysterectomy) with postmenopausal estradiol levels (\< 5 ng/dL)
  * Undergone bilateral oophorectomy

Performance status

* ECOG 0-2

Life expectancy

* At least 5 years

Hematopoietic

* WBC ≥ 3,000/mm\^3
* Platelet count ≥ 100,000/mm\^3

Hepatic

* Alkaline phosphatase ≤ 3 times upper limit of normal (ULN)
* AST ≤ 3 times ULN

Renal

* Creatinine \< 2.0 mg/dL
* No hypercalcemia (i.e., calcium \> 1 mg/dL above ULN within the past 6 months)
* No hypocalcemia (i.e., calcium \> 0.5 mg/dL below lower limit of normal within the past 6 months)

Other

* No uncontrolled infection
* No uncontrolled diabetes mellitus
* No uncontrolled thyroid dysfunction
* No disease affecting bone metabolism (e.g., hyperparathyroidism, hypercortisolism, Paget's disease, or osteogenesis imperfecta)
* No malabsorption syndrome
* No uncontrolled seizure disorder associated with falls
* No known hypersensitivity to zoledronate or other bisphosphonates, letrozole, calcium, or cholecalciferol (vitamin D)
* No mental illness that would preclude giving informed consent
* No other malignancy within the past 5 years except adequately treated basal cell or squamous cell skin cancer or carcinoma in situ of the cervix
* No other non-malignant systemic disease
* No clinical or radiologic evidence of existing fracture in the lumbar spine and/or total hip
* No history of fracture with low intensity or not associated with trauma
* No contraindication to spinal dual energy x-ray absorptiometry (DEXA) due to any of the following:

  * History of surgery at the lumbosacral spine, with or without implantable devices
  * Scoliosis with a Cobb angle \> 15° at the lumbar spine
  * Immobility, hyperostosis, or sclerotic changes at the lumbar spine
  * Evidence of sufficient sclerotic abdominal aorta that would interfere with DEXA scan
  * Any disease of the spine that would preclude proper acquisition of a lumbar spine DEXA
* Considered reliable

PRIOR CONCURRENT THERAPY:

Biologic therapy

* Not specified

Chemotherapy

* No concurrent chemotherapy

Endocrine therapy

* See Disease Characteristics
* Prior parathyroid hormone allowed provided it was not administered for \> 1 week
* More than 6 months since prior anabolic steroids or growth hormone
* More than 12 months since prior endocrine therapy (including estrogen) except for the following:

  * Tamoxifen
  * Insulin
  * Oral hypoglycemics
  * Thyroid hormone
  * Steroid inhalers
* More than 12 months since prior systemic corticosteroids except short-term corticosteroids to prevent or treat chemotherapy-induced nausea and vomiting or acute respiratory illness

  * Concurrent short-term corticosteroids allowed
* No other concurrent hormonal therapy
* No concurrent parathyroid hormone

Radiotherapy

* Not specified

Surgery

* Not specified

Other

* Prior systemic sodium fluoride allowed provided it was not administered for \> 3 months within the past 2 years
* More than 3 weeks since prior oral bisphosphonates
* More than 2 weeks since prior and no concurrent drugs known to affect the skeleton (e.g., calcitonin, mithramycin, or gallium nitrate)
* More than 30 days since prior systemic investigational drugs and/or devices
* More than 7 days since prior topical investigational drugs
* No prior IV bisphosphonates
* No prior aromatase inhibitor therapy
* No concurrent calcitonin, sodium fluoride, or Tibolone
* No other concurrent anticancer therapy
* No other concurrent bisphosphonates
* No other concurrent investigational drugs or devices