Overall the evidence included in the systematic review was of high quality.15 One trial, Spooner8, was rated as low quality evidence, as results were limited to one conference abstract. All trials included populations of over 700 women.15
All reported outcomes need to be considered in the context of the range of hypofractionated radiotherapy regimens that were evaluated. Although 50 Gy in 25 fractions was used as a control arm in all trials, six different hypofractionated radiotherapy regimens were investigated.
Not all trials were powered to detect a difference in all outcomes. RMH/GOC and the Canadian trial were powered to detect a difference in local tumour recurrence rates. START A and START B were powered to detect a difference in local-regional tumour relapse rate. The included trials had a follow-up period of 5-17 years.15