Letrozole in Treating Postmenopausal Women With Stage I, II or III Breast Cancer That Can Be Removed by Surgery

DISEASE CHARACTERISTICS:

* Diagnosis of invasive breast cancer

  * Clinical stage I, II, or III disease
  * Resectable disease
* Measurable disease, defined as a mass that can be reproducibly measured by physical examination and/or ultrasound and is at least 1 cm in size by ultrasound

  * Patients with measurable residual tumor at the primary site allowed
* Estrogen receptor-positive tumor by immunohistochemistry (IHC)
* HER2-negative tumor by Herceptest (0 or +1) OR HER2 not overexpressed by fluorescence in situ hybridization (FISH)
* Planning to undergo surgical treatment with either segmental resection or total mastectomy with or without lymph node evaluation
* Must have core biopsies from the time of diagnosis available (may include sections of paraffin-embedded material)
* Prior contralateral breast cancer allowed provided there is no evidence of recurrence of the initial primary breast cancer
* Patients with locally advanced disease who are candidates for preoperative chemotherapy at the time of initial evaluation are not eligible

  * Locally advanced disease is defined by any of the following:

    * Primary tumor ≥ 5 cm (T3)
    * Tumor of any size with direct extension to the chest wall or skin (T4a-c)
    * Inflammatory breast cancer (T4d)
    * Fixed axillary lymph node metastases (N2)
    * Metastasis to ipsilateral internal mammary node (N3)
* No locally recurrent disease
* No evidence of distant metastatic disease (i.e., lung, liver, bone, or brain metastases)

PATIENT CHARACTERISTICS:

* ECOG performance status 0-1
* Postmenopausal, as defined by any of the following:

  * 55 years of age and over
  * Under 55 years of age and meets 1 of the following criteria:

    * Amenorrheic for at least 12 months
    * Follicle-stimulating hormone (FSH) ≥ 40 IU/L and estradiol levels ≤ 20 IU/L
  * Has undergone prior bilateral oophorectomy or radiation castration AND has been amenorrheic for at least 6 months
* Bilirubin ≤ 1.5 times upper limit of normal (ULN)
* SGOT and SGPT ≤ 1.5 times ULN
* Creatinine ≤ 1.5 t times ULN
* Able to swallow and retain oral medication
* No serious medical illness that, in the judgment of the treating physician, places the patient at high risk for operative mortality
* No malabsorption syndrome, ulcerative colitis, or other disease significantly affecting gastrointestinal function
* No other malignancy within the past 5 years except for completely resected nonmelanoma skin cancer or successfully treated in situ carcinoma
* No dementia, altered mental status, or any psychiatric condition that would preclude the understanding or rendering of informed consent
* No severe uncontrolled malabsorption condition or disease (i.e., grade II/III diarrhea, severe malnutrition, or short gut syndrome)

PRIOR CONCURRENT THERAPY:

* See Disease Characteristics
* At least 21 days since prior tamoxifen or raloxifene as a preventive agent
* At least 7 days since prior hormone replacement therapy (e.g., conjugated estrogens \[Premarin\])
* No prior resection of the stomach or small bowel
* More than 30 days or 5 half-lives, whichever is longer, since prior investigational drugs
* No prior chemotherapy for this primary breast cancer
* No other concurrent investigational agents
* No other concurrent anticancer therapy (e.g., chemotherapy, radiotherapy, immunotherapy, hormonal therapy, or any other biologic therapy)