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 delivered by a machine outside the body, while brachytherapy or internal radiation therapy comes from radioactive material placed in the body near or within the tumour. EBRT is the most common method of delivering radiation treatment. Curative and palliative treatment regimens are usually given on an outpatient basis over 1–8 weeks. 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 and can require hospital admission. 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.