My brother has stage 3/4 esophageal cancer and has undergone radiation and chemo therapy . He t is 50 years old. He has one or two good days per week when he can get out of bed, but most other days he can t manage enough energy to get out of bed. A couple of my siblings who live in the same city as him feel that he should have more energy and think about the many people who seem to be able to function through treatments. He finished his treatments about 4 months ago. I think that treatment can affect people differently. Is it fairly normal for the exhaustion to affect some for this long. Certainly his pain and emotional worry are contributing.
How are his food intake-able to take solids or liquids only. If the there is problem to take both he should consult surgeon for other ways of feeding. He should take high protein, high carboy Chat Doctor.  Many food formulas are available. It is better he should try some of those, continue what he likes. Soups either vegetable or Nov veg can be give, and they are easily digestible also. Our aim with him is to give less quantity, frequent times, high caloric food. He should take small amount, of food in many times (not three times, large amount at a time, usually our habit of food intake).