Bone-modifying drugs help strengthen bones and are an important part of treatment for patients with breast cancer that has spread to the bones. The bone-modifying drugs used in the United States to treat bone metastases are pamidronate, zoledronic acid, and denosumab. Talk with your doctor about the differences between these drugs, including the cost, and the type of preventive care, such as dental care, that you'll need before taking a bone-modifying drug. It's also important to discuss the tests you'll need to monitor your health while taking a bone-modifying drug, as well as other ways to improve bone health.