The Role of Altered Fractionation in Head and Neck Cancers.

Abstract

At the present time, the only rigorously demonstrated therapeutic gain from altered fractionation in the treatment of head and neck cancer is in patients with intermediate stage oropharyngeal cancer treated with hyperfractionation in the Phase III EORTC Trial 2279 I.’ Nevertheless, there is a compelling radiobiological rationale and abundant suggestive evidence from a number of other clinical studies that a therapeutic gain may be realized more generally when conventional fractionation is modified by either reduction in size of dose per fraction, reduction in overall duration of the treatment, or both. This article will briefly review the background radiobiology of altered fractionation schedules and the clinical results that have been reported. The term “altered fractionation” is a relative one, because from the earliest days of radiotherapy there has been lack of agreement as to what constitutes the “norm.” Regimens regarded as conventional differ widely in different parts of the world. For example, in the Manchester school, radical (ie, definitive) treatments for head and neck cancer are dispensed in 16 fractions over 3 weeks while in the United States, most definitive treatments are administered in 35 to 40 fractions over 7 to 8 weeks. Many other variations exist in what is considered conventional therapy. To a large extent, the evolution of “conventional” dose fractionation schedules reflects logistic and financial considerations and the availability of equipment and staff as much as any serious effort to determine which fractionation schedule maximizes the therapeutic advantage. 2,3 Many schedules now considered unconventional have had their proponents in the past, but only recently has sufficient information been available to assess the merits of different fractionation schedules on a radiobiologic basis.