My friend says he doesn't care if he dies, and I don't know how to respond.

My friend smokes a lot of cigg's and thinks he might actually have cancer but won't go to the doctor cause he said if he does have it he wants it to be a surprise and just die without knowing. And he said he doesn't care if he dies and it's been bothering me like I'm not gonna force him to go to the doctor or anything but the words "I don't care if I die" is what's bothering me, I feel like he is being selfish kinda like I want to ask him, you don't care how your mom,brother or the rest of your family and friends feel? Like if it was actually cancer there is nothing you can do but hope but I feel like he implied those words just in general. As soon as he said to me "I don't care if I die" I was going to say "but I care!" but the convo. Got interrupted. This happens Sunday but I can't stop thinking about it and I don't know if I should bring it up again in a convo or just keep quite and let him deal with his life, he is the type of guy who listens only to himself and only takes advice if he is in the mood to hear it or seeking it. I really care for him and wouldn't want anything bad for him, I just don't know what to do...
My friend says he doesn't care if he dies, and I don't know how to respond.
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