Practical and clinical applications of radiation therapy

Radiation therapy utilizes 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 by far the most common method of delivering radiation treatment. Curative treatment regimens are usually delivered on an outpatient basis over a 3–8-week period. 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 may require hospital admission. While radiation therapy is usually described as a ‘local’ treatment, systemic radiation therapy is another strategy – use of 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 in various clinical situations, including the adverse effects of treatment.