FWIW, and I know it's a totally different cancer and probably not all that comparable, My dad is a 22 year survivor of colon cancer, had microscopic mets to one node that showed up in a careful pathology report, was advised, similarly to Gino, that radiation was optional, opted not to have it, and seems to have come out OK so far!
He may have been just lucky, and this was 22 years ago so he might get different advice these days, and I know it's a different cancer.
But it's also really possible this is a gray area when the mets are really microscopic and in one node that has been removed. Right after I had my neck dissection but before the path report ahd come back, my ENT actually mentioned to me this possibility and that if they only found "a few cells" it "would be a difficult decision" that I'd have to make.
I didn't have to make the decision about radaition because of that, as it turned out, but it makes me beleive many people think this is a gray area.
Nelie