Welcome to OCF. Everyone is different as you will quickly learn around here. Stage is important but I have seen some Stage I patients die while other Stage IV patients survive. I have been both, the last time I was Stage IV and I got thru it. So you see that your fathers Stage will not determine his fate.

Radiation for oral cancer patients can be very difficult. Nutrition and hydration are hard to get when its hard to swallow and things dont taste right. The nasal tube will help him to keep up with his required daily intake amounts. Around here we speak directly from experience. Your father needs 2500 calories and 48 oz of water every single day. It sounds like its alot but his body will be working overtime fighting not just the cancer but trying to rebuild itself. If he doesnt take this in he will have a much harder time getting thru this.

As far as the nausea goes, ask the doctor for anti-nausea meds like zofran and compazine to help him feel better. Once nausea hits its pretty hard to take in enough as whatever he throws up needs to be put back in. If necessary there are suppositories with some anti-nausea meds. Try to give the meds around the clock as once it gets away from you and he begins to throw up its almost impossible to get ahead of it.

Wishing you both all the best with everything!