Stress in child

Hello,

My best friend's son (4 years old) was diagnosed with cancer near his large intestine and liver. After surgery, he now has his large intestine attached to right side of his rib and a pouch receiving his bodily waste. Other than loosing his hair from chemo, this has caused the boy a lot of stress as he feels different and shameful of this pouch and do not want to go out. How should the parents deal with this?