Future issues in highly conformal radiotherapy for head and neck cancer.

Improving the conformity of the radiation dose to targets in the head and neck promises reduced toxicity and, in some cases, potentially improved local-regional tumor control. Intensity-modulated radiotherapy (IMRT) is a method that allows highly conformal delivery of radiotherapy. In recent years, its use has spread rapidly in both academic and community radiation oncology facilities. The use of IMRT has raised multiple issues related to target definition, optimal treatment delivery methods, and the need to account for anatomic changes occurring during therapy. Some of these issues are reviewed in this article.