You sound like you know more about his condition than I do.
What I remember is that he was given a 70% chance of survival over five years. I may be totally making that up, I don't know. Nonetheless, while he has a high probability of not surviving to the end of his term, with a prognosis like that there is no way of saying when death might come. Casey would be unable to plan, and if he looks like he's waiting for this "opportunity" to come, he looks very bad.