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