I understand very well how your father feels because I felt the same during my treatment a year ago. I was so weak after 30 rounds of radiation and 4 chemo (total dose was 48 radiation)that I was admitted to hospital for a drip and blood transfusion because my white blood cells count dropped to an intorable level. I was too threatened to get tube feeding if I could not eat. Drinking water was like a knife cutting your throat. Well you have no choice. Stopping treatment is a very unwise act because its effect on the tumour will be adversely affected. I lost over ten pounds but managed to take very soft food like cereal, congee and ice cream to maintain the nutrition to get the treatment through. So I didn't have a tube fixed for eating because I was simply too scared.So try to convince your father that either he exercises his strongest will power to eat or he gets a feeding tube. Skipping the treatment is not an option.