I can understand the "tiptoeing," but having been on the other end of that ... it's very uncomfortable for the patient, too---suddenly everyone treats you differently and seems to avoid you or be whispering about you. He may prefer to feel like he's the same guy you always knew. Quietly let him know that if he needs an ear, you're available to listen. Some patients don't want to burden anyone with their troubles, but it's a heavy, heavy load to carry alone all day. I know that suddenly having people tiptoeing around me (or worse, totally cutting themselves off from me because they felt awkward) made me feel like "dead woman walking," even though I had a good prognosis. I even grew to dread "Oh, you're looking so good today!" because it made me think: You must have expected me to look like a deathly ill wreck.
Sorry for the diatribe. But I felt I wanted to show the other side of the coin. It's uncomfortable on both sides, and the best thing for both sides is to not let the discomfort build barriers.