The optimal fractionation schedule has been an area of intense clinical research since the beginning of radiotherapy. Over the years, there have been many attempts to improve the outcome of radiotherapy by altering the overall treatment time, total dose, and number of fractions. The majority of clinical trials have tested hyperfractionation, accelerated fractionation, or their variants against "standard" once-daily fractionation. Altered fractionation radiotherapy has been most extensively studied in the treatment of head and neck cancer.
In this issue, Dr. Adam Garden succinctly reviews the rationale for hyperfractionation and accelerated fractionation, as well as the results of randomized clinical trials of altered fractionation radiotherapy in head and neck cancer. This will be a valuable reference for all those interested in this topic.
Improved Locoregional Control With Altered Fractionation
As Dr. Garden points out, the results of randomized trials thus far suggest that locoregional control in head and neck cancer can be improved by either an increased total dose (using hyperfractionation) or a shortened overall treatment time (using accelerated fractionation). However, there is no consensus about an "optimal" fractionation schedule. Indeed, the optimal fractionation schedule will be dictated by other practical considerations, such as patient compliance, available resources, and cost.
It should also be noted that the advantage of altered fractionation radiotherapy is seen primarily in patients with intermediate- to advanced-stage (stage II-IV) disease. Whether there is any therapeutic gain for early (stage I) disease has not been evaluated.
Normal Tissue Toxicity
Randomized trials of altered fractionation radiotherapy in head and neck cancer have consistently shown increased acute toxicity, primarily mucositis. Increased late effects in normal tissues also have been demonstrated with some accelerated fractionation schedules.