Reducing the Risk of Cancer Treatment-Associated Bone Loss in Patients With Breast Cancer

Women with breast cancer, especially those receiving aromatase inhibitors, are at higher risk for bone loss and fracture. Postmenopausal women may already have multiple risk factors for fracture, and breast cancer therapies compound these risks. Current guidelines for bone health management in women with breast cancer are based on bone mineral density (BMD) measurements; however, many risk factors for fracture are independent of bone mineral density. Thus, consideration of other risk factors for fracture, including cancer therapies, aromatase inhibitor therapy, and age, may be necessary to accurately identify patients at high risk for bone loss. Bisphosphonates, inhibitors of osteoclast-mediated osteolysis, may be efficacious for the prevention of aromatase inhibitor-associated bone loss. Several clinical trials evaluating zoledronic acid in this setting have produced favorable results. In the Austrian Breast and Colorectal Cancer Study Group (ABCSG)-12 trial, patients receiving anastrozole or tamoxifen plus goserelin experienced significant bone loss, and zoledronic acid treatment prevented bone loss in both groups. Results from the parallel studies Z-FAST, ZO-FAST, and E-ZO-FAST indicate that upfront zoledronic acid treatment increases BMD in patients receiving letrozole. These preliminary results are encouraging and suggest that zoledronic acid is an effective preventative therapy for bone loss in breast cancer patients receiving aromatase inhibitors.