Increased fracture rate in women with breast cancer: a review of the hidden risk

Background: Women with breast cancer, particularly individuals diagnosed at a relatively early age, have an increased incidence of fractures. Fractures can have serious clinical consequences including the need for major surgery, increased morbidity and mortality, increased cost of disease management, and reduced quality of life for patients. The primary cause of the increased fracture risk appears to be an accelerated decrease in bone mineral density (BMD) resulting from the loss of estrogenic signaling that occurs with most treatments for breast cancer, including aromatase inhibitors. However, factors other than BMD levels alone may influence treatment decisions to reduce fracture risk in this setting. Our purpose is to review current evidence for BMD loss and fracture risk during treatment for breast cancer and discuss pharmacologic means to reduce this risk. Results: Fracture risk during treatment for breast cancer may be influenced by the rate of BMD loss and the consequent rapid alterations in bone microarchitecture, in addition to the established fracture risk factors in postmenopausal osteoporosis. The rapid decrease in BMD during adjuvant chemoendocrine therapy for breast cancer may necessitate more aggressive pharmacotherapy than is indicated for healthy postmenopausal women who develop osteoporosis. Over the last few years, clinical trials have established the effectiveness of bisphosphonates and other antiresorptive agents to preserve BMD during adjuvant therapy for early breast cancer. In addition, some bisphosphonates (eg, zoledronic acid) may also delay disease recurrence in women with hormone-responsive tumors, thereby providing an adjuvant benefit in addition to preserving BMD and potentially preventing fractures. Conclusions: It is likely that a combined fracture risk assessment (eg, as in the WHO FRAX algorithm) will more accurately identify both women with postmenopausal osteoporosis and women with breast cancer who require bone-protective therapy.