Statement: the primary trial results show that Zoledronic Acid Upfront is a better treatment than Zoledronic Acid Delayed-start for preventing any change in Lumbar Spine (L1-L4) Bone Mineral Density (BMD).
Primary_evidence: Outcome Measurement:    Percent Change From Baseline in Lumbar Spine (L1-L4) Bone Mineral Density (BMD)   Bone mineral density (BMD) measurements were assessed by dual energy x-ray absorptiometry (DXA). The DXA devices of participating sites were cross-calibrated and the DXA results were compiled and analyzed by a central reader. Percent change = 100*((BMD at Month 12 - Baseline BMD)/Baseline BMD)). Missing data at month 12 were imputed by using the last observation carried forward (LOCF) method. Post-baseline non-missing data from month 6 were carried forward to month 12. Data prior to month 6 were not carried forward.   Time frame: Baseline, 12 months Results 1:    Arm/Group Title: Zoledronic Acid Upfront   Arm/Group Description: Participants in the upfront arm received Zoledronic Acid 4 mg i.v. on Day 1 and every 6 months until disease progression (recurrence)or the end of study. Participants also received Letrozole 2.5 daily plus calcium (1000-1200 mg) and vitamin D (400-800 IU) daily.   Letrozole : Participants received 2.5 mg daily.   Zoledronic Acid : Participants received Zoledronic Acid 4 mg IV 15-minute infusion every 6 months.   Overall Number of Participants Analyzed: 253   Mean (Standard Deviation)   Unit of Measure: Percentage of BMD  1.955         (3.3658) Results 2:    Arm/Group Title: Zoledronic Acid Delayed-start   Arm/Group Description: In lieu of a placebo arm, which was considered unethical for this trial, a delayed start arm was used. Participants who met certain clinical criteria indicating risk of lumbar spine or total hip fracture, or experienced clinical fracture unrelated to trauma or any asymptomatic fracture discovered at the Month 36 scheduled visit, were started on zoledronic acid 4 mg i.v. and for every 6 months until disease progression (recurrence) or end of study. Participants also received Letrozole 2.5 daily plus calcium (1000-1200 mg) and vitamin D (400-800 IU) daily.   Letrozole : Participants received 2.5 mg daily.   Zoledronic Acid : Participants received Zoledronic Acid 4 mg IV 15-minute infusion every 6 months.   Overall Number of Participants Analyzed: 256   Mean (Standard Deviation)   Unit of Measure: Percentage of BMD  -2.325         (3.9542)