I took "not an option" as meaning he has no choice, but to get a peg tube lol. In the absence of sepsis, I agree with the above, and if not a peg tube, due to possible infection fom surgery, stomach issues, at least an NG tube. If not that, Total Patental Nutrition, TPN, through the port instead. How is his weight? Doctors get concerned when 10 percent of the body weight is lost, and may even cease treatment when it gets closer to 20 percent.
There is a link how one manages through treatment, and their overall survival. Ones that do better, have less adverse effects do better than those that don't in the long run. Stopping radiation is not good either, and gives the chance for cancer to repopulate.
I'm not too sure about the reduction of radiation, and why, to reduce toxicities?They may be reducing the delivery volume for now, and accelerate it later on, or give a boost dose at the end, and still get the total intended doses of Gy as recommended by treatment protocols.