Do any of you know of any research/information wrt diet and cancer recovery?

I have a young family member who was diagnosed with brain cancer at the age of 5. He is now nine and is currently cancer free . However the treatments he received have given him, among other things, blindness and a significant loss of hearing. Also he has just recently started a regimen of daily injections of growth hormone as he has not developed significantly since his diagnosis. He still catches a lot of stuff too because his immune system isn't up to par.

He is a neat kid and great to be around. One of my big concerns for him though is his diet. He doesn't eat much and when he does it's pretty much the SAD - chicken nuggets, pizza, coke, hot dogs, french fries, mac and cheese, cookies, some fruit, som...e yogurt, you get the idea. And some drink in a drink box called Boost, to give him extra calories. I think his parents are probably so glad to see him eating anything and getting calories that what he eats isn't too important. I can see that side of things.

BUT, I am convinced that if they would start giving him no grains, healthy fats, and whole foods, that he would have a significant improvement in all areas. I am not a doctor or a nutritionist. I guess his doctors and/dietician aren't overly concerned and haven't said much about what he should eat. I'm not sure how much his parents would buy into anything I say.

We've been a lot healthier since eating this way, but usually most of my family/inlaws (many of whom also have various diet-related health issues) just smile and nod when I talk about the benefits of cutting out grains and veering away from the SAD. So I'm not sure they would be convinced to try this. I just want to help this kid some way!