DISEASE CHARACTERISTICS:

• Diagnosis of breast cancer

  • T2-T4c, any N, M0 disease

• Clinically staged, as documented by the operating surgeon, as 1 of the following:

  • T4a-c disease for which modified radical mastectomy with negative margins is the goal
  • T2 or T3 disease for which conversion from needing mastectomy to breast conservation is the goal
  • T2 disease for which lumpectomy at first attempt is the goal
• Primary tumor must be palpable and measure > 2 cm by tape, ruler, or caliper measurements in at least one dimension
• Must agree to undergo mastectomy or lumpectomy after neoadjuvant aromatase inhibitor therapy
• No inflammatory breast cancer, defined as clinically significant erythema of the breast and/or documented dermal lymphatic invasion (not direct skin invasion by tumor or peau d'orange without erythema)

• No distant metastasis (M1)

  • Isolated ipsilateral supraclavicular node involvement allowed
• No diagnosis that was established by incisional biopsy

• Must have estrogen receptor (ER) positive tumor with an Allred score of 6, 7 or 8

  • Patients with > 66.66% (two-thirds) of cells staining positive and have a minimum Allred score of 6 are eligible

PATIENT CHARACTERISTICS:

• ECOG/Zubrod performance status of ≤ 2
• Female

• Patient must be postmenopausal, verified by 1 of the following:

  • Bilateral surgical oophorectomy
  • No spontaneous menses ≥ 1 year
  • No menses for < 1 year with FSH and estradiol levels in postmenopausal range

• No other malignancies within the past 5 years, except for successfully treated cervical carcinoma in situ; lobular carcinoma in situ of the breast; contralateral ductal carcinoma in situ that was treated with mastectomy or lumpectomy with radiotherapy (without tamoxifen); or non-melanoma skin cancer with no evidence of recurrence

  • Must have undergone potentially curative therapy for all prior malignancies AND deemed to be at low risk for recurrence, according to the treating physician

PRIOR CONCURRENT THERAPY:

• No prior treatment for invasive breast cancer, including radiotherapy, endocrine therapy, chemotherapy, or investigational agents
• No prior sentinel lymph node biopsy (cohort B only)
• At least 1 week since prior agents with estrogenic or putatively estrogenic properties, including herbal preparations
• At least 1 week since prior hormone replacement therapy of any type, megestrol acetate, or raloxifene
• No concurrent enrollment in another neoadjuvant clinical trial for treatment of the existing breast cancer
• No other concurrent anti-neoplastic therapy, including chemotherapy or radiotherapy
• No concurrent agents or herbal products that alter ER function