The influence of a seventy-two hour gap on the acute response of mouse skin and oesophagus

Abstract

The sparing effect of a 72 h gap, inserted after the third, sixth or ninth fraction of a 12 fraction X-ray schedule, was investigated in two early responding normal tissues: mouse skin and oesophagus. Acute skin reactions and body weight loss were used as assays to quantify changes in the radiation tolerance of these tissues. In skin, no evidence of compensatory proliferation was seen if a gap was inserted, whatever its position in the schedule. In oesophagus, a small but significant increase in radioresistance was observed if the gap was positioned 1/4 of the way through treatment compared with the schedule delivered without an interruption (12F/12 days). Although an increase in normal tissue tolerance is not observed by increasing the overall time from 12 to 15 days, provided tumour clonogen proliferation does not occur during the weekend split, the insertion of a gap makes continuous accelerated clinical regimes, currently given without an interruption at weekends, easier to introduce into wider clinical practice.