In addition, other studies have reported on the acute toxicities and patient-reported outcome. One randomized controlled trial reported by Paelink et al demonstrated no increase in moist desquamation after SIB in a randomized trial of 167 patients(27). Another randomized controlled trial compared hypofractionated radiotherapy with SIB to conventionally fractionated radiotherapy with sequential boost. The shorter regime resulted in better recovery of functional status and faster recovery from fatigue.(28).

The results from the IMPORT - High trial as presented at SABCS 2018 demonstrate that SIB (48 Gy) was associated with similar rates of moderate to severe breast induration, shrinkage, distortion and change in photographic appearance as a sequential boost (40 Gy + 16 Gy). A mild to marked change in photographic appearance was observed in 12 patients undergoing SIB versus 35 patients undergoing sequential boost (p=0.03)(29).

If the results of FAST-FORWARD trial are positive, one-week whole breast radiotherapy may be adopted as a standard of care in the UK. However, this study has been conducted in a predominantly screen detected Caucasian population. Advanced cancers, and also younger patients with triple negative cancers are under-represented. In our population, the majority of patients need a tumour bed boost and thus in order to have a truly one-week course of radiotherapy, the tumour bed boost needs to be delivered as a SIB.

Hence a trial investigating a one-week whole breast radiotherapy schedule with a SIB for the tumour bed needs to be conducted in our setting. We therefore plan to integrate a FAST-FORWARD like one-week radiotherapy schedule with a SIB with appropriate dose reduction as done in the IMPORT-High trial.