Background: In women with early-stage breast cancer, bone is a common site of distant recurrence and represents approximately 40% of all first recurrences. Preclinical studies demonstrated that inhibition of RANKL significantly delays skeletal tumor formation, reduces skeletal tumor burden, and prolongs survival of tumor-bearing mice. Denosumab is approved for the prevention of skeletal-related events (SREs) in patients with established bone metastases from solid tumors. The D-CARE trial is designed to assess if denosumab treatment prolongs bone metastasis-free survival (BMFS) and disease-free survival (DFS) in the adjuvant breast cancer setting. The primary endpoint of this event-driven trial is BMFS. Secondary endpoints include DFS and overall survival. Additional endpoints include safety, breast density, time to first on-study SRE (following the development of bone metastasis), patient reported outcomes, and biomarkers. Methods: In this international, randomized, double-blind, and placebo-controlled phase 3 trial, 4509 women with stage II or III breast cancer at high risk for recurrence and with known hormone and HERE2 receptor status were randomized. High risk was defined as biopsy evidence of breast cancer in regional lymph nodes, tumor size > 5 cm (T3), or locally advanced disease (T4). Standard-of-care adjuvant or neoadjuvant chemo-, endocrine, or HER-2 targeted therapy, alone or in combination, must be planned. Patients with a prior history of breast cancer (except DCIS or LCIS) or distant metastasis, oral bisphosphonate (BP) use within 1 year of randomization, or any intravenous BP use, were not eligible. Patients were randomized 1:1 to receive denosumab 120 mg or placebo subcutaneously monthly for 6 months, then every 3 months for a total of 5 years of treatment. Supplemental vitamin D (≥ 400 IU) and calcium (≥ 500 mg) were required. The trial, sponsored by Amgen Inc., began enrolling patients in June 2010 and completed enrollment in late 2012. Clinical trial information: NCT01077154.