RATIONALE: Gathering information over time from bone density and laboratory tests of women with breast cancer treated with triptorelin and tamoxifen or exemestane may help the study of breast cancer in the future.

PURPOSE: This clinical trial is studying changes in bone mineral density in women with breast cancer treated with triptorelin and tamoxifen or exemestane on protocol IBC SG-25-02 (TEXT).

OBJECTIVES:

• Evaluate changes in bone mineral density (BMD) among premenopausal women randomized in protocol IBC SG-25202 (TEXT-2) to receive either: A) triptorelin (GnRH analogue) for 5 years plus tamoxifen for 5 years; or B) triptorelin (GnRH analogue) for 5 years plus the steroidal aromatase inhibitor exemestane for 5 years.
• Evaluate serial serum markers for bone remodeling (C-telopeptide, osteocalcin, bone-specific alkaline phosphatase) and investigate their correlation with BMD.
• Evaluate the relationship of genetic variants of CYP19A1, ERα, ERß, and IGF 1 with BMD.
• Evaluate serial serum growth factors (IGF-1 and IGFBP-3) and investigate whether their time course correlates with BMD.
• Explore the role of serum IGF-1 and IGFBP-3 as biomarkers of disease outcome (disease-free survival). (exploratory)

OUTLINE: Blood samples are collected at baseline and then periodically for 6 years. Serum markers of bone remodeling and serum growth factor levels are measured.

Bone mineral density in the L1-L4 (postero-anterior) region of the spine and femoral neck of the hip is measured by DEXA at baseline and then periodically for 6 years.

Any surplus serum is stored for use in unspecified future research.

DISEASE CHARACTERISTICS:

• Patient must be eligible and enrolled in the TEXT-2 trial prior to enrolling in TEXT-Bone
• Serial bone marrow density (BMD) measurements must be taken within the same institution
• Hormone receptor positive

PATIENT CHARACTERISTICS:

• See Disease Characteristics
• Premenopausal
• No bone fracture in the past 6 months that, in the investigator's judgement, could be related to bone fragility
• No clinical or biochemical malabsorption syndrome, known vitamin D deficiency, active hyper- or hypoparathyroidism, or Paget's disease
• No uncontrolled thyroid disease, Cushing disease, or other pituitary diseases
• No other bone disease (including osteomalacia or osteogenesis imperfecta)

PRIOR CONCURRENT THERAPY:

• See Disease Characteristics
• At least 6 months since prior and no concurrent bisphosphonate therapy (or other bone therapies such as PTH or strontium)
• At least 6 months since prior glucocorticoid (> 5 mg prednisone or equivalent) for > 1 month
• At least 12 months since prior anticonvulsants