[Bone-related events in breast cancer]

Breast cancer most frequently causes bone metastases in solid tumors. It has been known that there is a vicious cycle consisting of tumor cells, osteoblasts, osteoclasts and various humoral factors in osteolytic lesions. Although systemic therapy is a main treatment of bone metastases, local therapies, such as radiotherapy and surgical therapy, are also promptly needed when bone-related complications occur. In recent years, anti-osteoclast agents, bisphosphonates significantly contribute to the delay of occurrence of bone-related complications. Postoperative adjuvant therapy significantly reduces the incidence of recurrence in breast cancer patients. Chemotherapy and LH-RH agonists cause ovarian function suppression in premenopausal patients, and aromatase inhibitors cause estrogen deprivation in postmenopausal patients. These effects cause unbalance of bone metabolism, loss of bone density and increase in the incidence of fractures. Improvement of these bone-related adverse effects and careful follow-ups are needed for breast cancer patients.