Pete,
I was admitted into the hospital because I couldn't swallow anything at all and needed to be fed and hydrated by IV. He just showed up at my bedside the next day, so I guess the hospital Doc-in-charge called him in.
Since then, my disability Medicare became effective. I chose Humana Gold (with Medicare) to manage my health care, so since then it's a referral from my Primary Care Provider - everything's supposed to go through her now.
That hasn't been a problem for me because she's very easy to get along with and doesn't question anything I need. Before I signed with Humana I made sure that they would have no problem with all cancer-related issues going through Shands too. That was a deal-breaker for me, and so far,so good.
I don't know, but probably ENTs would also do the procedure. Check with your PCP, or your cancer Doc should be able to help out, too, if you need a referral. Maybe you could just call on your own, though, if your insurance allows it. Gastroenterologists take care of the whole "gastro" thing top to bottom - esophogus, stomach, and on to that colonoscopy we're all supposed to get. (So if you go in to have your esophogus dilated, don't let them tell you to strip from the waist down.)

Do this. I promise you'll be thrilled with the results.
Lani