Does the molecular subtype of breast cancer influence your decision to give hypofractionated radiotherapy?

I heard Jay Harris speak at ACRO last year and the Dana Farber/Brigham has a personalized BCT approach based on molecular subtype

‘Personalized’ BCT based on Subtype, Age (DFCI/BWH)

Luminals Age > 60: 266 x 16, no boost

Luminals Age 50-60: 266 x 15, 250 x 2

HER2+ Age > 50: 266 x 15, 250 x 4 < 50: 200 x 22 + 200 x 8 = 60 Gy

TN: Conventional + concurrent platinum on protocol

At this point for patients who need breast RT only we do not distinguish based on phenotye for offering hypofractionation . Start B did not see any difference in outcome in any sub category. Whelan data when reviewed showed no difference in outcome for two fractionation for nottingham grade 3 disease. High grade is independent factor for local recurrence and we make sure all these patinets get boost with hypofractionation also

It’s not exactly obvious to me that there is any example where response to radiotherapy fraction size alone is affected by tumor grade alonewithin a particular disease subsite. This should be clearly distinguished from the potential/theoretical benefit of dose escalation in biologically-unfavorable disease. In my mind, this issue has really been settled since 2010, when a meta-analysis of RMH, START A, START B trials was reported as a short communication in the NEJM (Yarnold, et al. NEJM 362:1...

The new ASTRO guideline on whole breast fractionation recently published in Practical Radiation Oncology (PRO) recommended that the decision to offer hypofractionation should be independent of grade, ER, PR, Her2/neu status or margin status. There was 100% consensus on this question by the panel of experts. I continue to offer hypofractionation, independent of tumor subtype. They did note, based on low levels of evidence, that conventional fractionation may be preferred when treating rare histol...