RATIONALE: Aromatase inhibitor therapy is used in treating postmenopausal women who have hormone-dependent breast cancer. It is not yet known what effect aromatase inhibitor therapy has on blood vessel function.

PURPOSE: This clinical trial is studying the effect of aromatase inhibitor therapy on blood vessel function in postmenopausal women with breast cancer.

OBJECTIVES:

• Determine the effect of adjuvant aromatase inhibitor therapy on endothelial function in postmenopausal women with breast cancer.

OUTLINE: This is a multicenter study. Patients are assigned to 1 of 2 treatment groups according to breast cancer hormone-receptor status (positive vs negative).

• Group 1 (hormone receptor-positive): Patients receive aromatase inhibition therapy for up to 6 months in the absence of unacceptable toxicity.
• Group 2 (hormone receptor-negative): Patients do not receive adjuvant treatment.

Endothelial function is measured in both groups at baseline and at follow up by the room temperature peripheral arterial tonometry (RT-PAT) index using the EndoPAT method.

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

Patients with recently diagnosed breast cancer