Don,
Most that have treatment for HNC have swallow issues with or without the tube. The rate which those that do get a peg tube, who will be dependent on it long term is 10%, depending on study, and many other factors are involved. The average time otherwise is 21 weeks to 7 months, dependng on study, and seems those that have it pre-treatment, as opposed to reactively, may be more long term dependent.
Seems this is a more recent concern with newer treatment options, and just in my time, 2009, it was recommended peg tubes be placed. I also remember about that time a big uproar with Medicare/Medicaid about the high incident of unecessary peg tube placements in nursing facilities, and the need to reduce that. I don't know if that crack down had any effect in the medical community all around.
The Peg Wars continue lol.