Current and emerging treatment strategies for breast cancer-induced bone loss.

Breast cancer increases a woman's risk for bone loss. Bone loss occurs due to the skeletal fragility associated with malignancy, the occurrence of premature ovarian failure secondary to chemotherapy, and the loss of bone mineral density (BMD) associated with antiestrogen therapies. Tamoxifen has been shown to reduce BMD among premenopausal women, and aromatase inhibitors, which have become a standard therapy among postmenopausal women, increase bone loss and the risk of fracture. Bisphosphonates preserve BMD among women with breast cancer, both among postmenopausal women and those with a history of significant bone loss. The effect among premenopausal women appears modest. Despite the protective effect on bone density, a reduction in the risk of fracture has not yet been established. Therefore, other risk factors for fracture must be addressed, such as dietary intake, vitamin D, and assessment of other potentially modifiable conditions. Newer agents that target the receptor activator of nuclear factor-κB (RANK) system and RANK ligand (RANKL), such as denosumab, represent an emerging class of medications that may also preserve BMD in this population.