For a young female (<40) with HR-/HER2+ cT1-2N1, ypT1aN0 s/p mastectomy with SLNB, would you offer PMRT?

Thanks for the question. In the seminal PMRT randomized trials of patients treated with adjuvant systemic therapy, PMRT improved overall survival. B-51 was not designed to evaluate the non-inferiority of PMRT omission. Beyond being less conservatively designed to test for superiority of "RNI" with r...

I would be very uncomfortable omitting radiotherapy in this patient.

The patient is young which is associated with higher locoregional recurrence rates. The B-51 follow-up is short and the patient had residual disease in the breast. I appreciate the excellent summary of Dr. @Dr. First Last.

Had the ...

I agree with Dr. @Dr. First Last's points about patients undergoing mastectomy and SLNB being underrepresented on B-51 and therefore using caution when applying the conclusions of B51 to these patients.

I would also use caution when interpreting ypN0 in this case. There is evidence that after neoadju...

I would favor no RT although I doubt there is consensus with people having different interpretations of B-51.

Our institutional policy is to offer RT based on the initial stage (preneo adj) so yes we would offer.