Would you ever omit adjuvant radiation for a patient with rectal cancer originally staged cT1N0, but found to be pT1N1 after surgery?

Certainly a topic that comes up not uncommonly in tumor boards. The gold standard comparing pre to post operative chemoradiation remains the German colorectal trial, and showed increase in acute diarrhea from 12% to 18% and long term GI sx from 9% to 15%, strictures from 4% to 12%. Although there is an increased risk, the absolute increased risk is low and the benefit of adjuvant radiation is proven. I do still recommend radiation after surgery.

No

SOC answer is to treat the pelvis based on Sauer and others with the goal to reduce LRR.

I think it is important to realize that this is the type of risk group that may not get the maximal benefit. Gunderson et al. performed a great pooled analysis to break down these groups, and trimodality for T1-T2 N1 does not seem significantly additive (and this was in a different era of systemic).

I would expect this node to be a perirectal node and would be curious about the size of the node and any other...

No