A single--blind, randomized, placebo--controlled phase II study to evaluate the impact of oral bisphosphonate treatment on bone mineral density in osteopenic women receiving aromatase inhibitors as adjuvant treatment.

Aromatase inhibitors (AIs) are the adjuvant treatment of choice in postmenopausal women with early, hormone receptor-positive breast cancer (BC), because they produce improved survival rates compared with tamoxifen. Progressive bone loss and subsequent fractures are associated with adjuvant AIs, administered either alone or sequentially after tamoxifen in postmenopausal women with early BC. Recent findings of National Surgical Adjuvant Breast and Bowel Project (NSABP) B-34 also suggest that bisphosphonates might have anticancer benefits for older postmenopausal women. "BONADIUV" trial is a single-blind, randomized, placebo-controlled study designed to evaluate the impact of bisphosphonate treatment on bone mineral density (BMD) in women taking AIs.

Patients undergo a baseline BMD and if they result osteopenic (lumbar spine and/or trochanter -1< T-score <2.5), they are randomized in a 1:1 ratio to receive either placebo or oral ibandronate. All patients receive oral supplementation of calcium and Vitamin D3, once daily for two years. Study duration is 2 year, with planned six-months evaluation.

A total of 72 patients per arm of treatment are needed to obtain a 85% statistical power in order to detect a 2% BMD mean difference between the two arms. Considering a 15% dropout, around 82 patients per arm are planned to be enrolled.

Inclusion Criteria:

• Diagnosis of hormone-receptor positive early breast cancer
• Menopausal status
• Age < 75 years
• Written informed consent

Exclusion Criteria:

• Premenopausal status at time of randomization
• Comorbidities with increased risk of osteoporosis (primary hyperparathyroidism, hyperthyroidism, rheumatoid arthritis)
• BMI < 18
• Chronic use of steroids
• Use of bisphosphonates at time of randomization
• Psychiatric disorders