RATIONALE: Estrogen can cause the growth of breast cancer cells. Hormone therapy using anastrozole may fight breast cancer by lowering the amount of estrogen the body makes.

PURPOSE: This phase II trial is studying how anastrozole effects postmenopausal women who have undergone surgery for ductal carcinoma in situ or stage I, stage II, or stage III breast cancer.

OBJECTIVES:

Primary

• Determine the 12-month change in breast density in postmenopausal women with ductal carcinoma in situ (DCIS) or stage I-III breast cancer treated with adjuvant anastrozole.

Secondary

• Determine the change in estrone sulfate levels in patients treated with this drug.
• Correlate the change in breast density with the change in circulating estrone sulfate levels in patients treated with this drug.
• Determine the frequency of polymorphisms in aromatase (CYP19) and evaluate the relationship between wild-type aromatase enzyme with change in breast density and change in estrone sulfate levels in patients treated with this drug.
• Determine the 12-month change in bone density, and correlate it with the change in circulating estrone sulfate levels in patients treated with this drug.
• Correlate the reversal of hypermethylation with change in circulating estrone sulfate levels and breast density in patients treated with this drug.

OUTLINE: This is a pilot study. Patients are stratified according to concurrent bisphosphonate use (yes vs no).

Patients receive oral anastrozole once daily for up to 12 months in the absence of disease progression or unacceptable toxicity.

PROJECTED ACCRUAL: A total of 50 patients will be accrued for this study.

DISEASE CHARACTERISTICS:

• Histologically confirmed breast cancer meeting 1 of the following criteria:

  • Ductal carcinoma in situ (DCIS)

  • Invasive carcinoma

    • Stage I-III disease

• Must have undergone breast cancer surgery within the past 6 months, including any of the following:

  • Mastectomy or lumpectomy with or without radiation
  • Sentinel node and/or axillary node dissection
  • Re-excision of lumpectomy margins

• Intact contralateral breast

  • No prior radiation therapy or mastectomy
  • Prior biopsies allowed

• Hormone receptor status:

  • Estrogen and/or progesterone receptor-positive tumor by immunohistochemical staining

PATIENT CHARACTERISTICS:

Sex

• Female

Menopausal status

• Postmenopausal, defined as 1 of the following:

  • At least 60 years of age
  • Less than 60 years of age and amenorrheic ≥ 12 months prior to study entry
  • Less than 60 years of age, amenorrheic for < 12 months prior to day 1, and luteinizing hormone (LH) and follicle stimulating hormone (FSH) values within postmenopausal range
  • Less than 60 years of age, without a uterus, and LH and FSH values within postmenopausal range
  • Underwent prior bilateral oophorectomy
  • Underwent prior radiation castration AND amenorrheic for ≥ 6 months

Performance status

• ECOG 0-2

Life expectancy

• Not specified

Hematopoietic

• Not specified

Hepatic

• Not specified

Renal

• Not specified

PRIOR CONCURRENT THERAPY:

Chemotherapy

• No prior or concurrent adjuvant chemotherapy for breast cancer

Endocrine therapy

• No prior aromatase inhibitor

• At least 6 weeks since prior and no concurrent tamoxifen

• At least 6 weeks since prior and no concurrent hormone replacement therapy

  • Concurrent low-dose, local vaginal estrogen in the form of either a conjugated estrogen ring or other similar product (e.g., Estring® or Vagifem®) allowed

• At least 6 weeks since prior and no other concurrent selective estrogen receptor modulators (e.g., raloxifene)

Radiotherapy

• See Disease Characteristics

Surgery

• See Disease Characteristics
• No contralateral breast implant

Other

• Concurrent bisphosphonates allowed at the discretion of the treating oncologist

• No concurrent consumption of soy supplements

  • Concurrent routine dietary consumption of soy-containing foods allowed

• No other concurrent investigational or commercial drugs or therapies for the treatment of DCIS or invasive breast cancer