Undecided.

Top Line: Few trials are mentally cited by rad oncs on a daily basis more than EORTC 22922 (aka the Poortmans trial).

The Study: Here we have 15 year results, which are still trying to distinguish a difference in overall survival with the addition of adjuvant comprehensive regional nodal irradiation (RNI) for intermediate risk breast cancer. As a reminder, this behemoth international phase 3 trial enrolled over 4000 women with either axillary disease or a medial primary tumor. Survival at 15 years was statistically similar at 71% without and 73% with the addition of RNI. Neither were there differences in disease-free (60 versus 61%) nor mets-free (68 versus 70% ) survival. So what does RNI improve in the long term? What we already knew from previous reporting: rates of breast cancer recurrence (27.1 → 24.5%) and breast cancer mortality (20 → 16%). In other words, this does little to convert undecided voters. Opponents of RNI will state such advantages simply aren’t worth the additional toxicity, some of which may actually work to counteract any breast cancer survival advantage. Proponents will then counteract that the toxicity of contemporary techniques is much improved since the conventional single anterior supraclavicular field matched to tangents employed in most cases here, widening the therapeutic window.

TBL: The decision to pull the trigger on regional nodal irradiation is probably better made when weighing myriad individual risk factors we now know predict recurrence risk than when applying broadly to the grabbag of patients enrolled in EORTC 22922. | Poortmans, Lancet Oncol 2020