Myelopathy and hyperfractionated accelerated radiotherapy: a radiobiological interpretation.

Abstract

Where there is a rapid repopulation of tumor clonogens, a gain in local control should be realized by administering radiation treatments in a shorter overall time, thereby reducing the opportunity for proliferation of tumor cells during the treatment. Because of the differential effect of fractionation in early-versus late-responding normal tissues, decreased overall treatment time must be done in the context of keeping the fraction size small. The only feasible approach is to administer multiple fractions per day and use short interfraction intervals. Provided repair of sublethal radiation damage is largely complete within the interfraction interval, excessive late morbidity would not be expected. These radiobiological rationales of accelerated hyperfractionated radiotherapy thus suggest an altered fractionation scheme in which the overall treatment time is reduced, the dose per fraction is reduced, and multiple fractions are given per day.KeywordsPrincess Margaret HospitalSmall Fraction SizeSublethal DamageRepair KineticRadiation MyelopathyThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.