Short and long fractionated schedules in radiotherapy and a proposed improvement.

Abstract

This paper compares the “northern UK” practice in radiotherapy (of using short overall times and a small number of relatively large fractions) with the “southern UK and elsewhere” practice (of using overall times as long as 6–7 weeks and 30–35 fractions of 2 Gy). Neither of these methods is optimal. The “northern” schedule uses doses per fraction which are, in principle, too large, but this calculable disadvantage is offset by a usefully short overall time, at least in tumours which proliferate fast. The “southern” schedule uses overall times which may be too long for the fast-proliferating tumours, but this disadvantage is offset by the use of smaller doses per fraction, which spare late reactions more than they spare early reactions or tumour cell kill. Because both types of existing schedule are predictably suboptimal, although for different reasons, it can be predicted that neither type of schedule will show a distinct advantage over the other in clinical results. We are now beginning to understand th...