Would you consider ultra-hypofractionated 5 fraction regional nodal radiation in a node + breast cancer who otherwise wouldn't tolerate 16 fractions of RT?

At this time, unless there was a strong reason that hypofractionated breast + RNI in 15-16 fractions couldn't be done, I wouldn't use 5 fx breast + RNI off-trial. If compelling reasons, one could consider extrapolating safety of breast RT from FAST/FAST-Forward and axilla from melanoma data.