Head and neck cancer: altered fractionation schedules.

Local control is paramount in the treatment of localized advanced head and neck cancer. Standard radiotherapy cures a high percentage of early tumors--more than 80% of the early laryngeal tumors--but fewer of the advanced tumors. Attempts have therefore been made to improve the therapeutic ratio by: A) hyperfractionation: reducing the dose per fraction to reduce late morbidity; the total dose is then elevated in an attempt to improve local tumor control with equal morbidity, and B) acceleration: reducing the overall treatment time to overcome repopulation during a protracted course of radiotherapy. The total dose and dose per fraction have been reduced in the accelerated arm in some trials, while in others the total dose has been maintained. Both these strategies have been tested in multicenter randomized controlled trials, but neither have become part of routine clinical practice. The biological parameters determining local tumor control and normal tissue effects are being studied at Mount Vernon by an analysis of selected randomized controlled trials, with the aim of designing new schedules of radiotherapy for future studies.