DD1s fiend had a lot of chemo from when she was 5 (YR until she was 7 (I think). She had leukemia and was quite ill with it. She is now in Y4 and if you didn't know about it you would never guess. Things I can remember is that she lost all her hair, but it wasn't an issue at school - kids were very accepting (probably more than if she'd been older). She also got tired a lot, and she had a big buggy to be carted around in when she had had her chemo (has 3 siblings). Areas that were affected were swimming - she was only allowed to go recently (started about 12 months) but now swims like a fish, and school obviously, but the school gave as much help as they could & she has now caught up with her peers. Sorry I can't give much info, we really didn't know them that well at the time, have got friendly in the last 18 months or so. How old is your friends ds?