Effect of Aromatase Inhibitor Therapy on Blood Vessel Function in Postmenopausal Women With Breast Cancer

DISEASE CHARACTERISTICS: * Diagnosis of breast cancer * Ductal carcinoma in situ (DCIS) allowed provided the patient will not receive tamoxifen as part of treatment for their cancer * May not have had a prior mastectomy with requirement for mastectomy of the contralateral breast * No requirement for axillary lymph node dissection with a history of contralateral mastectomy and/or contralateral axillary lymph node dissection * Hormone receptor status meeting 1 of the following criteria: * Hormone receptor negative and not eligible for aromatase inhibitor therapy (AI) * Hormone receptor positive and are not receiving an AI PATIENT CHARACTERISTICS: * Postmenopausal * No known or symptomatic coronary artery disease * No significant co-morbidities, including any of the following conditions: * Active renal or hepatic disease * Known uncontrolled and/or untreated peripheral arterial disease * Uncontrolled and/or untreated hypertension * Uncontrolled and/or untreated diabetes * Uncontrolled and/or untreated hyperlipidemia PRIOR CONCURRENT THERAPY: * See Disease Characteristics * More than 7 days since prior hormone replacement therapy or hormone-based contraception * More than 12 months since prior and no concurrent tamoxifen or aromatase inhibitor therapy for this disease * More than 12 months since prior and no concurrent chemotherapy for this disease * No prior bilateral mastectomy