Clinical and practical applications of radiation therapy: when should radiation therapy be considered for my patient?

Radiation therapy uses high-energy radiation from X-rays, γ-rays, neutrons, electrons, protons and other sources to kill cancer cells and shrink tumours. External-beam radiation therapy (EBRT) is a form of radiation therapy delivered via a machine outside the body, while brachytherapy is a form of internal radiation therapy, which comes from radioactive material placed in the body near or within the tumour. EBRT is the most common method of delivering radiation treatment. Curative treatment regimens are usually given on an outpatient basis over a 1–8-week period. Palliative treatment regimens range from a single treatment to up to 2 weeks' duration. Chemotherapy is sometimes given concurrently with radiation therapy and acts as a radiation sensitizer. Brachytherapy is most frequently used to treat prostate and gynaecological cancers. Although radiation therapy is usually described as a ‘local’ treatment, systemic radiation therapy uses a radioactive substance, such as a radiolabelled monoclonal antibody, that travels throughout the body via the bloodstream. This article describes the role of radiation therapy and its adverse effects in various clinical situations.