Your doctors may have a reason for saying that, usually from too much weight loss, and as Don said, not enough nutrition, and hydration or concern of that. Radiation also continues to work for 6 weeks after treatment, and the last two weeks are the worst, so treatments effects just doesn't stop on the last day.

I went into induction chemo without a peg, but was soon hospitalized from a chemo reaction, so one was put in at one point, which I vaguely remember, and not the next day..but after a month. I could not eat, drink, not even have ice by mouth, just an IV. It's done by endoscope, and not cut open. Anyway, when I had it taken out, the scar was smaller than a dime. When I had treatment the 2nd time, I had another put in, and still lost 30 lbs. For my situation, it was best. I did not have too much problems eating afterwards, and soon ate everything.

Good luck with your decidion, and the rest of your treatments.