I also have "fight for life at all cost" experience, though only with animals (I provided a kitty foster home, and through that assisted in a vet clinic somewhat). It's not like with humans, but enough.
I have also seen my grandfather's last days, so maybe that influences me somewhat.
If I ever get cancer, barring some incredibly lucky circumstances when it's completely resolvable, I will avoid treatment. The suffering is not worth it, and the pressure on the loved ones is not just financial.