Lance, cancer is horrible (I'd use stronger language except that I see you're a good Christian and I don't want to shock you). Not only does it take over our lives, it takes over the lives of everyone around us.
We must worry about ourselves, and let other people worry about themselves. So we do whatever we can for our loved ones: update the will, let them know how much we love them, make sure that they have people to support them, and so on. And after that, we can be more selfish, and trust to them to be strong enough to cope.
Incidentally, have you come across the "Ring Theory" of dealing with life's horrors? http://www.latimes.com/opinion/commentary/la-oe-0407-silk-ring-theory-20130407,0,6378839.story#axzz2nloXHfZF
I find it helps.