Tamoxifen Versus Anastrozole, Alone or in Combination With Zoledronic Acid

The trial is conducted as an open multi-center phase III study, in a two-factorial study design and according to Good Clinical Practice (GCP) guidelines. Patients will be randomly assigned to a total of 4 study groups in a 1:1:1:1 assignment ratio. Several stratification criteria will be used in order to ensure balanced distribution of known risk factors. A total of 1.803 patients will be enrolled in 4 arms. Patients will either be treated with anastrozole (1mg daily for 3 years) or tamoxifen (20mg daily for 3 years), and will additionally receive either zoledronate (8mg q4 weeks for 3 years) or no zoledronate (arm A: Nolvadex alone; arm B: Nolvadex plus zoledronate; arm C: Arimidex alone; arm D: Arimidex plus zoledronate). Zoledronate will be administered by i.v. injection at a dose of 4 mg/month for the treatment period of 3 years. Five Bone Mineral Density (BMD) measurements will be performed in a subgroup of patients (404 patients, enrolled in 3 centres).