For breast patients that are clinically node negative based on ultrasound and axial imaging, is axillary radiation an acceptable alternative to axillary dissection in a setting where a sentinel lymph node fails to map?  

Standard in this situation is ALND. In the era when anatomy along with phenotype and genomic score drive systemic treatment options, it’s reasonable to do high tangent RT instead of ALND to avoid risk of lymphedema unless systemic treatment would change based on nodal status.

This is similar to a question asking about what to do if the patient did not get SLNBx. If clinically low risk, whole breast RT alone may be ok. Most of my patients would get high tangents in this scenario since I don't think our surgeons would automatically proceed with ALND.