section_path: Management/Radiation
section_name: Radiation
paragraph_text: Radiation
  
  Radiation therapy involves the use of ionizing radiation in an attempt to either cure or improve symptoms. It works by damaging the DNA of cancerous tissue, causing mitotic catastrophe resulting in the death of the cancer cells. To spare normal tissues (such as skin or organs, which radiation must pass through to treat the tumor), shaped radiation beams are aimed from multiple exposure angles to intersect at the tumor, providing a much larger dose there than in the surrounding, healthy tissue. As with chemotherapy, cancers vary in their response to radiation therapy.
  
  Radiation therapy is used in about half of cases. The radiation can be either from internal sources (brachytherapy) or external sources. The radiation is most commonly low energy X-rays for treating skin cancers, while higher energy X-rays are used for cancers within the body. Radiation is typically used in addition to surgery and or chemotherapy. For certain types of cancer, such as early head and neck cancer, it may be used alone. Radiation therapy after surgery for brain metastases has been shown to not improve overall survival in patients compared to surgery alone. For painful bone metastasis, radiation therapy has been found to be effective in about 70% of patients.