I sympathize with your dad. I was just as stubborn and I did make it thru my radiation treatments without a feeding tube.
But it was a tremendous struggle about this same time, half way thru treatment, when I could no longer eat solid food. I lived on Ensure Plus (vanilla). Yes it would have been easier for me to get a tube, and yes, I lost weight, but I did get thru it and it meant a lot to me psychologically.
I had to shake my head reading this, remembering how I did not care nor listen to what my wife , my sister, my doctors thought about getting a feeding tube. As if anyone could make me get one. so, yes try and get him a tube, but don't blame yourself if he refuses. 7 lbs in a week out of 280 does not sound like much to me. I was only sixty years old though and went from 177 to 134, but I had a lot of lean muscle mass and almost zero fat. So can it be done, yes if the patient is stubborn enough and can stand everybody saying his objection is stupid and dangerous, and forces down Ensure Plus.
I never got dehydrated nor needed to go into the hospital.
For me it was the right choice and I never regretted it.
For the majority of patients, without a psychological motivation (damn cancer will not force me to have a tube, I will swallow and eat), a tube is better
It can't hurt to talk to him but it is his decision
Charm