A terminal diagnosis turns you into a part-ghost. The spectre of your absence shadows you like a bad private investigator-- it's always visible and not especially discrete. Walk in a room and the ghost part of you reminds everyone of their own mortality, and god knows no one wants to think about that. Your double nature discomfits them, and you find people not quite willing to look you in the eye, or sort of sliding away as if you and they are both magnetized. If you ever need someone to break up a party that's gone on too long, just give me a call.
I recently saw a facebook post asking how to talk to someone with Stage IV breast cancer. I think what the poster really meant was how to talk to a ghost; how to address and support a person who is only partly there. The ghost part of me is an intimidating bully, hovering over conversations and whispering "DEATH" is a raspy, Scooby Doo villain voice. The ghost part of me, though, isn't really part of me, more like something that clings to me but is separate. The closest analog I can come up with right now is those horrible head brace things some poor kids had to wear to correct scoliosis. It's always with me, but it's not me, and it freaks people out. But unlike the head brace, I don't get to take it off, and there's no end-date for its torments. Or I suppose there is, but not one I know or look forward to.
And that end date could be far away-- some women live with this disease more than 5 years, some even 10 years. Occasionally, more than 20, though that's rare. Whenever it is for me, until then, I'm alive. I have good days and bad. I sleep way more than anyone should, and sometimes there's more pain than my impressive arsenal of opioids can handle, but in general I'm okay, and still myself. I'm negotiating with the ghost by eating a ridiculously heathy diet, taking a ridiculous number of supplements under the care of a naturopathic doctor, working with various modes of meditation and energy healing, and trying to tap into hope as much as I can.
I think that's actually the answer to "how do you talk to someone with Stage IV Cancer." Talk to them like you've always talked to them-- they're still the same person they always were. Talk to them with hope, real hope, and you will help them banish the douchebag ghost.