Regarding regional nodal irradiation for triple positive breast cancers, how much do you weigh in the availability of effective adjuvant systemic therapies (i.e, hormonal and anti-Her2 therapy) in theory being able to control subclinical nodal disease without the need for RT consolidation?

Borderline cases such as patients that received NAC with a complete response or N1 disease with 1-3 positive nodes make me think frequently about this issue, especially if the patients are already at higher risk for lymphedema or with left-sided tumors. There is at least retrospective evidence for anti-Her2 therapy contributing to locoregional control in the setting of BCT, as expected (Kiess at al Cancer 2012). It will be some time before NSABP B-51 sheds some light in the NAC/pCR setting, but even then the triple positives will only be a subgroup within the whole population. The largest retrospective series that I know of (Arsenault et al AJCO 2013) addressing trastuzumab-containing NAC in Her2-amplified tumors points to RT omission as a predictor of LRR (50% with regional component), but one could ask if that still holds with dual anti-Her2 therapy. Just wondering how people are weighing everything in their practice patterns, thanks in advance for your thoughts!