How would your elective nodal coverage change in a patient with anal cancer metastatic to a high external iliac node?

I agree with the comments above, but I have an additional comment. For some reason as a field, we have pushed the dose to electively treated regions to 45 Gy, although there are no data in the literature to justify that high a dose. I would extend the radiation fields to the celiac axis but would limit the dose to the PA nodes to 30.6 Gy. In the original Nigro report, 30.6 Gy (with drug) controlled gross disease. You do not need 45 Gy to effectively treat microscopic extension. You get better coverage with less toxicity at a lower dose.

PA nodes should be designated N2, not M1. Elective coverage is an important consideration. It's a judgement call how far up to cover. I agree with @Dr. First Last's comments and recommendation if it was just one ext iliac node. However, it is not common to have direct spread to an ext iliac node without inguinal in involvement from anal cancer. If the adenopathy was more extensive (intentionally undefined), that tells you about the biology of that case and I prefer to consider covering higher. I use the transverse duodenum as a landmark. That is the only structure that could cause increased toxicity. So I either stop before I get there if I think a patient needs extended coverage, or I go all the way to just above the celiac axis if there w...

If it was a high external iliac node and small bowel positioning was favorable, I’d extend superiorly to the aortic bifurcation to include the common iliac nodes, i.e. 1 lymph node echelon above.