Long-term implications of bone loss in breast cancer.

Cancer treatment-induced bone loss (CTIBL) is an emerging problem during long-term adjuvant therapy with aromatase inhibitors or ovarian-ablative therapy. CTIBL increases the risk of skeletal complications. Patients receiving adjuvant therapy for breast cancer should receive periodic bone mineral density (BMD) assessments, and those with clinically significant bone loss should be treated with bisphosphonates. Intravenous (i.v.) bisphosphonates (e.g., zoledronic acid) appear to be a very effective treatment for CTIBL. Recently, the Austrian Breast and Colorectal Cancer Study Group 012 trial reported that i.v. zoledronic acid (4 mg every 6 months) maintained BMD in premenopausal women receiving goserelin with either tamoxifen or anastrozole. The Z-FAST and ZO-FAST trials are comparing i.v. zoledronic acid (4 mg every 6 months) up front with letrozole versus initiation when patients exhibit lumbar-spine BMD T-scores > or =2 standard deviations below normal (i.e., T-score < or =-2.0). These studies will provide important insight into the management of CTIBL.