Premenopausal Endocrine Responsive Chemotherapy Trial (PERCHE)

DISEASE CHARACTERISTICS: Histologically confirmed breast cancer confined to the breast and axillary nodes No distant metastatic disease Tumor detected in the internal mammary chain by sentinel node procedure allowed Must have undergone 1 of the following procedures for primary breast cancer within the past 12 weeks and have no known clinical residual locoregional disease: Total mastectomy with or without adjuvant radiotherapy Breast-conserving surgery (e.g., lumpectomy, quadrantectomy, or partial mastectomy with margins clear* of invasive cancer and ductal carcinoma in situ) followed by radiotherapy NOTE: *If all other margins are clear, a positive posterior (deep) margin is permitted, provided the excision was performed down to the pectoral fascia and all tumor has been removed OR a positive anterior (superficial; abutting skin) margin is allowed provided all tumor was removed Prior axillary lymph node dissection or negative axillary sentinel node biopsy required Patients with microscopically positive axillary sentinel nodes allowed provided they were evaluated on a clinical trial evaluating microscopically positive lymph nodes No locally advanced, inoperable breast cancer, including any of the following characteristics: Inflammatory breast cancer Supraclavicular node involvement Enlarged internal mammary nodes (unless pathologically negative) No prior ipsilateral or contralateral invasive breast cancer Histologically diagnosed synchronous bilateral invasive breast cancer within the past 2 months allowed if the bilateral disease meets all other eligibility criteria Hormone receptor status: Estrogen receptor and/or progesterone receptor positive in each tumor At least 10% of tumor cells positive by immunohistochemistry PATIENT CHARACTERISTICS: Age Premenopausal Sex Female Menopausal status Premenopausal Estradiol in the premenopausal range after surgery Performance status Not specified Life expectancy Not specified Hematopoietic Not specified Hepatic No systemic hepatic disease that would preclude prolonged follow-up Renal No systemic renal disease that would preclude prolonged follow-up Cardiovascular No prior deep venous thrombosis and/or embolism unless patient is medically suitable No systemic cardiovascular disease that would preclude prolonged follow-up Pulmonary No systemic pulmonary disease that would preclude prolonged follow-up Other Not pregnant or nursing Fertile patients must use effective nonhormonal contraception No other prior or concurrent invasive malignancy except adequately treated basal cell or squamous cell skin cancer, nonbreast carcinoma in situ without invasion, contralateral or ipsilateral carcinoma in situ of the breast No prior or concurrent nonbreast invasive malignancy within the past 5 years that is nonrecurrent including any of the following: Stage I papillary thyroid cancer Stage Ia carcinoma of the cervix Stage Ia or b endometrioid endometrial cancer Borderline or stage I ovarian cancer No other nonmalignant systemic disease that would preclude prolonged follow-up No history of noncompliance with medical regimens No psychiatric, addictive, or other disorder that would preclude study compliance or giving informed consent PRIOR CONCURRENT THERAPY: Biologic therapy Not specified Chemotherapy No prior neoadjuvant or adjuvant chemotherapy Neoadjuvant or adjuvant trastuzumab (Herceptin®) allowed Endocrine therapy No prior neoadjuvant or adjuvant endocrine therapy after breast cancer diagnosis No prior tamoxifen or other selective estrogen-receptor modulator (e.g., raloxifene) within 1 year before the breast cancer diagnosis No other concurrent oral or transdermal hormonal therapy, including any of the following: Estrogen Progesterone Androgens Aromatase inhibitors Hormone replacement therapy Oral or other hormonal contraceptives, including implant and depot injections Raloxifene or other selective estrogen-receptor modulators Radiotherapy See Disease Characteristics No prior ovarian irradiation Surgery See Disease Characteristics No prior bilateral oophorectomy Other No other prior neoadjuvant therapy No other concurrent investigational agents No concurrent bisphosphonates unless bone density has been documented at least 1.5 standard deviations below the young adult normal mean or the patient is participating in a randomized clinical trial setting testing bisphosphonates in the adjuvant breast cancer setting