Of all people diagnosed with cancer, 25% will have their cancer come back and spread to the bones. This often results in significant pain and suffering. Radiation treatment is often recommended as a safe and quick treatment that gives most people good relief from bone pain within a couple of weeks. However, some people can experience a short episode of increased pain called a flare a day or two after radiation treatment that lasts about a day. Studies suggest that around a third of all people who receive radiation treatment to help pain from cancer in the bones will have a pain flare. This study is being done because it would be helpful to prevent extra bone pain from happening to people after they receive radiation treatments. The purpose of this study is to find out if a medication called dexamethasone can help prevent pain flare as a result of radiation therapy.