I'm not sure whether you're most concerned about his illness or the chemotherapy - or maybe both?

I don't know from what you say about what his condition is but I can say that chemotherapy isn't always as bad as people picture it.

When my wife's cancer was diagnosed she was started on carboplatin - that's a platinum chemotherapy which is the P in BEP. She sat in a comfy chair for a few hours and we chatted as she was hooked up and the drugs pumped in ad we left thinking "Was that it?" a couple of days later she had some flu like symptoms for a day or so and then that was it for the next 3 weeks no real sickness - but she did talk for about 8 hours straight immediately after due to the steroids.

Now I know some people have a much tougher time of it and there are are the other chemo drugs in this regieme (the B and the E) but you'll also find a lot of people on here who expected something a lot worse and have been on chemo for a long time.He'll be worried too but when you ask someone if they're OK they'll probably just say yes because - well what else do you say? My advice is to try to be as normal as possible and try to help take his mind off of it 

Best of luck with the treatment,