Principles of chemotherapy and radiotherapy

The management of most malignancies is multidisciplinary with chemotherapy and radiotherapy widely employed. The reasons tumours are destroyed and normal tissues recover after radiotherapy are complex and thought to be due to differences in intrinsic radiosensitivity and ability to repair and repopulate. Linear accelerators, which produce “skin-sparing” photons (high energy X-rays), are used to treat deep-seated tumours. Brachytherapy (short distance treatment) with implanted or internal radiation sources can also be used.Chemotherapy consists of drugs of different classes and modes of action, which may be used in combination to prevent drug resistance. Cytotoxic agents affect normal and malignant cells leading to a variety of side-effects. Chemotherapy can be given with radiotherapy to enhance the therapeutic effect. With advances in the understanding of the molecular biology of cancer, targeted therapies are now being used in clinical practice. Chemotherapy can be used with curative or palliative intent.