What Do You Say To A Dying Coworker ?

A coworker of mine who is not well liked and who was recently demoted, just found out he has 2-4 weeks to live. His wife is throwing him a "lifes" end party next week for all to say goodbye one last time. I am the only one attending from my work area, as I think it's the right thing to do. However, I am at a loss as to what to talk about. I can't talk with him of the future as he has none. I really don't want to discuss work due to his recent demotion and the fact that no one else from here is attending the party. I also feel that talking about his upcoming demise is too much of a sore subject to touch upon. Perhaps I can just listen and take cues from him and his wife and go from there. Any suggestions ?