Radiotherapy

Modern radiotherapy shapes beams to the tumour from many angles (IMRT, image-guided and stereotactic techniques) so that the tumour gets a lethal dose while surrounding tissue gets much less; treatment is usually split into daily fractions over one to seven weeks to let normal tissue repair, though ultra-short courses (SBRT) are increasingly used. It is a local therapy, curative on its own in early prostate, larynx, cervix and skin cancers, combined with chemotherapy in head and neck, lung, oesophageal and rectal cancers, and used after surgery to sterilise the operative bed. Protons and carbon ions spare more normal tissue; radiation may also help immunotherapy by releasing tumour antigens (the abscopal effect), and radioligand therapy delivers radiation internally through a targeting molecule.