Intensity-modulated radiation therapy in the treatment of head and neck cancer.

Intensity-modulated radiation therapy (IMRT) is a new technical improvement of radiotherapy, in which computer-controlled treatment machines produce multiple beams of radiotherapy whose intensity is optimized to deliver a high dose of radiation to specified volumes, while reducing the dose to adjacent non-target organs. The potential benefits include the ability to deliver higher doses to the target with an improved safety than has previously been possible, and to reduce side effects and complications. Using IMRT to treat some head and neck cancers is especially attractive due to the close vicinity of the targets and many critical, dose-limiting and non-involved structures, and because of the lack of breathing-related motion. The main clinical uncertainties in the use of IMRT for head and neck cancer relate to uncertainties in the extent of radiation to the target areas. In addition, large volumes of adjacent, non-target tissue receive moderate to low radiation doses, raising concerns of increased risk of radiation-related carcinogenesis in young patients. Initial promising clinical data have emerged from IMRT treatment of several head and neck tumor sites.