Bilateral femoral head osteonecrosis in a patient with metastatic breast cancer receiving long-term zoledronic acid treatment: A case report

Bone-modifying agents (BMAs), including bisphosphonate and anti-receptor activator of NF-kappa B ligand (RANKL) antibodies, are effective in treating bone metastases. The present study is a case report on the efficacy and side effects of long-term treatment with zoledronic acid, a BMA, in a 57-year-old woman. The patient was diagnosed with concurrent stage IV triple-negative breast cancer and stage II colon cancer. The patient experienced complete remission of both these cancers following chemotherapy, zoledronic acid treatment and irradiation for breast cancer and surgery for colon cancer. The patient received long-term zoledronic acid treatment and has survived >7 years after her initial diagnosis. The patient subsequently reported bilateral hip pain that was diagnosed as osteonecrosis of the femoral head, after the presence of bone metastases was ruled out using magnetic resonance imaging. The patient underwent bilateral artificial hip joint replacements. After orthopedic surgery, the multiple distant metastases, including a brain metastasis, remained in complete remission. It is well established that BMAs, such as zoledronic acid, increase the risk of osteonecrosis of the jaw, but it is not well understood if they can increase this risk in other anatomical locations. The findings of the present case study suggested that while long-term use of BMAs may be effective in managing bone metastases, it may increase the risk of osteonecrosis in anatomical locations other than the jaw.