Use of monthly oral ibandronate to prevent anastrozole-induced bone loss during adjuvant treatment for breast cancer: Two-year results from the ARIBON study

554 Background: The ARIBON trial is a double-blind, randomized, placebo-controlled study designed to evaluate the impact of bisphosphonate treatment on bone mineral density (BMD) in postmenopausal women taking adjuvant anastrozole for their endocrine responsive breast cancer. Methods: BMD was assessed in 131 patients prior to commencing adjuvant endocrine treatment. 68, 50, and 13 patients were found to be normal (T >-1.0, group 1), osteopenic (T -1.0 to -2.5, group 2), and osteoporotic (T <-2.5, group 3), respectively. All patients were treated with anastrozole 1mg once a day and calcium and vitamin D supplementation. In addition, group 2 patients were randomized on a 1:1 basis to receive either treatment with oral ibandronate 150 mg every month or placebo. Group 3 patients were treated with open label oral ibandronate 150mg every month. BMD and bone marker measurements were repeated at regular intervals for two years. Group 1 patients were followed up on calcium and vitamin D supplements alone. Results:...