Hi there. I think by giving him radiation the second time around they are trying to make sure that it is gone. The new tissue is clean but that doesn't mean there isn't any microscopic cancer still hanging around. Paul is right radiation is very focused. Might he end up on a peg for life, there are a few people here who are, or it may simply become more difficult for him to eat, or if he continues to eat and drink even small amounts and goes for therapy after he may be fine - it really depends on the individual. I think at this point it is a quality of life issue - you say he is healthy and in good shape? Then - while not being able to take foods by mouth is completely sucky - it might be a good trade off if it means he can spend the next 20-30 years with his family.
hugs