The role of intensity-modulated radiotherapy in head and neck cancer.

Intensity-modulated radiotherapy (IMRT) has been a significant technological advance in the field of radiotherapy in recent years. IMRT allows sparing of normal tissue while delivering radical radiation doses to the target volumes. The role of IMRT for parotid salivary gland sparing in head and neck cancer is well established. The utility of IMRT for pharyngeal constrictor muscle and cochlear sparing requires investigation in clinical trials. The current evidence supporting the use of IMRT in various head and neck subsites has been summarized. Sparing of organs at risk allows for dose-escalation to the target volumes, taking advantage of the steep dose-response relationship for squamous cell carcinomas to improve treatment outcomes in advanced head and neck cancers. However, dose-escalation could result in increased radiation toxicity (acute and late), which has to be studied in detail. The future of IMRT in head and neck cancers lies in exploring the use of biological imaging for dose-escalation using targeted dose painting.