Which early stage breast cancer patients who are candidates for 3-week hypofractionated whole breast EBRT are not good candidates for 1-week whole breast EBRT?  

One important dosimetric criteria for 5.2 x 6 is V105 of 5% or less and v 107 of 2% or less.  For 3 week RT, our data suggest v105 < 10% caused less morbidity. These dose homogeneity constraints are sometimes hard to meet for moderate or large size breasts and one need to be careful. Also ...

I agree with the answer above. My approach would be to continue to offer 5 fractions selectively during COVID (and after), when protocol specified dosimetric constraints can be met. I have selectively used 5 fractions (per FAST or FAST FORWARD) for a couple of years in appropriate circumstances, and...