Are there situations in which hypofractionated breast RT is acceptable after neoadjuvant chemotherapy and lumpectomy?

In my practice, I routinely offer hypofractionated whole breast radiation plus a boost (40 Gy/15 fractions plus 10-14 Gy in 5-7 fractions, as per START B) to any patient 40 and older who has received neoadjuvant chemotherapy and lumpectomy, provided my target is the breast only or breast plus low axilla. I think this practice approach is a very reasonable extrapolation of the START A/B and Canadian hypofractionation trials.

Until we have a greater volume of data demonstrating the safety of hypofractionated regional nodal irradiation, my standard of care will continue to be conventional fraction following neoadjuvant chemotherapy and lumpectomy if regional nodal irradiation is indicated.

At our institution, we routinely do hypofractinated RT for women 50 and above after neoadjuvant chemo and BCS, as long as nodal region is not required to be treated. In the START B trial patients who had adjuvant chemo were included and had no difference in outcome.