DISEASE CHARACTERISTICS:

• Patients must either be concurrently enrolling or previously enrolled to Canada (CAN) National Cancer Institute of Canada (NCIC) study MA.32 (CAN-NCIC-MA.32) (MA.32); eligible patients may be either pre- or post-menopausal

• Patients must have hormone receptor-negative breast cancer

• Patients must have breast density ≥ 25% (correlating with the Breast Imaging-Reporting and Data [BIRAD]-2 category of "scattered fibroglandular densities" or greater)

• Baseline digital mammograms taken within 12 months prior to registration to MA.32, with at least a craniocaudal (CC) view used for enrollment to MA.32 must be available for submission; if the patient has previously enrolled to MA.32 and one year has elapsed from baseline mammograms, one-year mammograms must also be available for submission

• Contralateral unaffected breast in place (with no prior cancer or radiation, no implants, and no plan for breast surgery on contralateral breast over the course of the study); women with a prior biopsy on the unaffected breast are eligible

PATIENT CHARACTERISTICS:

• Not specified

PRIOR CONCURRENT THERAPY:

• See Disease Characteristics

• Women receiving endocrine therapy (e.g., tamoxifen, aromatase inhibitors) are not eligible

N/A

• Obstetrics and Gynecology

• Oncology (Adult)

• Cancer and Leukemia Group B