Low-dose Oral Cyclophosphamide and Methotrexate Maintenance for Hormone Receptor-negative Early Breast Cancer

DISEASE CHARACTERISTICS:

* Histologically confirmed stage I, II, or III breast cancer

  * T1-3, N0-2, M0

    * Patients with sentinel node biopsy positive disease must have undergone axillary dissection
    * Tumor must be confined to the breast without detected metastases elsewhere
  * T4 disease with minimal dermal invasion allowed
  * No T4 disease with ulceration of skin, infiltration of skin (except pathologically minimal dermal involvement), peau d'orange, or inflammatory breast cancer
* No bilateral breast cancer (except in situ carcinoma) or suspicious mass in opposite breast that has not been proven benign
* No distant metastases

  * No skeletal pain of unknown cause, elevated alkaline phosphatase, or bone scan showing hot spots that cannot be ruled out as metastases by x-ray, MRI, and/or CT
* Must have undergone prior total mastectomy OR breast-conserving procedure (e.g., lumpectomy, quadrantectomy, or partial mastectomy with negative margins) with radiotherapy planned

  * Patients must begin or have begun an approved induction chemotherapy regimen within 8 weeks after definitive surgery
* Negative surgical margins
* Axillary clearance with at least 6 lymph nodes examined OR negative sentinel node biopsy
* Known HER2 status by immunohistochemistry or fluorescence in situ hybridization
* Hormone receptor status:

  * Estrogen and progesterone receptor negative

    * Less than 10% positive tumor cells by immunohistochemistry

PATIENT CHARACTERISTICS:

Age:

* Not specified

Sex:

* Not specified

Menopausal status:

* Premenopausal, defined as less than 6 months since last menstrual period (LMP) AND no prior bilateral ovariectomy AND not on estrogen replacement (OR under age 50) OR
* Postmenopausal, defined as prior bilateral ovariectomy OR more than 12 months since LMP without prior hysterectomy (OR age 50 and over)

Performance status:

* Not specified

Life expectancy:

* Not specified

Hematopoietic:

* WBC greater than 3,000/mm3
* Platelet count greater than 100,000/mm3

Hepatic:

* See Disease Characteristics
* Bilirubin less than 2.0 mg/dL
* ALT less than 1.5 times upper limit of normal OR AST less than 60 IU/L

Renal:

* Creatinine less than 1.2 mg/dL

Other:

* Not pregnant or lactating within the past 6 months
* Fertile patients must use effective barrier contraception
* No other prior or concurrent malignancy except adequately treated basal or squamous cell carcinoma of the skin, carcinoma in situ of the cervix, or contralateral or ipsilateral in situ breast carcinoma
* No psychiatric or addictive disorders that would preclude study
* No non-malignant systemic disease that would preclude study

PRIOR CONCURRENT THERAPY:

Biologic therapy:

* Prior trastuzumab (Herceptin) allowed

Chemotherapy:

* See Disease Characteristics
* No prior adjuvant or neoadjuvant chemotherapy for breast cancer

Endocrine therapy:

* No prior endocrine therapy for breast cancer or prevention
* No prior tamoxifen or raloxifene for breast cancer

Radiotherapy:

* No prior radiotherapy for breast cancer except primary irradiation

Surgery:

* See Disease Characteristics

Other:

* No prior preventative therapy for breast cancer