Radiotherapy: practical applications and clinical aspects

Radiation therapy involves the use of high-energy radiation from X-rays, γ rays, neutrons, electrons, protons, and other sources to kill cancer cells and shrink tumours. Radiation may come from a machine outside the body (external-beam radiation therapy), or it may come from radioactive material placed in the body near cancer cells or within the tumour (brachytherapy or internal radiation therapy). External-beam radiation therapy is by far the commonest method of delivering radiation treatment. Curative treatment regimens are usually delivered on outpatient basis and extend over a 4–8-week period. Chemotherapy is sometimes given during this time as a radiation sensitizer. Brachytherapy may involve a hospital admission and, over the past two decades, there has been a major increase in the use of this approach in prostate and gynaecologic cancers. While radiation therapy is usually described as a ‘local’ treatment, systemic radiation therapy is another strategy – using a radioactive substance, such as a radiolabelled monoclonal antibody, that travels in the blood to tissues throughout the body. This article will describe the role of radiation therapy in various clinical situations, including the side effects of treatment.