He needs proper nutrition and hydration or he'll slide into a black hole - his body needs proper food, (or ensure, boost etc...) to boost his immune system and help him heal so that the chemo and rads can do their job efficiently. People do not realize how delicate our body is in terms of nutritional balance and healing. I have never understood people who don't do whatever they can to get he best possible outcome. Tell him it takes 12 swallows (for me - I'm a woman) to chug an ensure. He only has to do it 5 - 6 times a day - depending on how calorie dense it is - it takes less than a minute and will give him the protein and nutrition required to heal - without it - it will take longer even after treatment - to get back to almost normal. Also radiation and chemo damage tissues. So aside from fighting infection, having to maintain normal body function, and fight cancer - he has to heal. Lack of proper nutrition along with hydration, stalls all that progress. Ps ramen noodles have limited nutritional value. I too got by without a peg as I couldn't use the one they put in, but the end of treatment and first week post treatment were the worst and to make up for not eating - I chugged high protein shakes. Best of luck.