Letrozole With or Without Zoledronate in Treating Healthy Postmenopausal Women With High Breast Density

OBJECTIVES: Primary * Compare the percent change in breast density in healthy postmenopausal women with high breast density treated with placebo only vs letrozole and placebo vs letrozole and zoledronate. * Compare the percent change in biochemical markers of bone turnover in participants treated with these regimens. Secondary * Compare the bone density in participants treated with these regimens. * Compare growth hormone release and insulin-like growth factor levels in participants treated with these regimens. * Compare the incidence and severity of adverse events in participants treated with these regimens. OUTLINE: This is a randomized, placebo-controlled, double-blind, multicenter, pilot study. Participants are stratified according to prior hormone replacement therapy (HRT) use (discontinued HRT \> 5 years ago or no prior HRT use vs discontinued HRT 1-5 years ago). Patients are randomized to 1 of 3 treatment arms. * Arm I: Participants receive oral placebo once daily for 12 months and placebo IV over 15 minutes on day 0 and at 6 months. * Arm II: Participants receive oral letrozole once daily for 12 months and placebo IV over 15 minutes on day 0 and at 6 months. * Arm III: Participants receive oral letrozole once daily for 12 months and zoledronate IV over 15 minutes on day 0 and at 6 months. In all arms, treatment continues in the absence of unacceptable toxicity. After completion of study treatment, participants are followed at 3 months. PROJECTED ACCRUAL: A total of 120 participants (40 per treatment arm) will be accrued for this study.