Secondary bone cancers. Frontal X-ray of the base of the pelvis in a patient with secondary cancers (metastases) in the pelvic bones. They are seen as the less dense bone areas at lower left, where the bone is degenerating. These cancers spread (metastasized) from a primary cancer elsewhere in the body. Secondary cancers are treated by whole body (systemic) methods, such as anti-cancer drugs that target the cancer cells that have spread. Metastatic bone cancers can be treated with beam radiotherapy. Bone cancers cause severe pain, and often the spread of the cancer is irreversible and the prognosis is poor.