Simply show that you care about him, and understand what is going on with his heath. I have to say by taking the step to come on here is hugh, in showing him that you care and are concerned about his heath.
Does he come on here? I have found a lot of great support, even if you do not contirbute it is nice to know that you are not the only one out there going through this stuff.
I assume that you are graduating in 08, and hes about the same age.... Check out the adult section, there could be more info there that you/ he could relate to.
Best of luck.