"Being Mortal" by Atul Gawande talks about this. He mentions Stephen Gould's essay, "The Median Isn't The Message," in which Gould says:
> For most situations, however, I prefer the more martial view that death is the ultimate enemy—and I find nothing reproachable in those who rage mightily against the dying of the light.
Which is an idea I think meshes very well with the strategy of chasing low probability , high reward outcomes. Gawande's response makes a lot of sense to me personally:
> There is almost always a long tail of possibility, however thin. What's wrong with looking for it? Nothing, it seems to me, unless it means we have failed to prepare for the outcome that's vastly more probable. The problem is that we have built our medical system and culture around the long tail. We've created a multitrillion-dollar edifice for dispensing the medical equivalent of lottery tickets—and have only the rudiments of a system to prepare patients for the near certainly that those tickets will not win. Hope is not a plan, but hope is our plan.
He also talks about several patients he treated through the years who suffered through futile treatments while trying to become one of the lucky ones and lost what quality of life they might have had in their dwindling time.
I'm glad your sister was one of the lucky ones who had a good outcome as opposed to going through the major surgery and chemo and being one of the 95%. It also seems to me that a different mindset in these sort of situations that educate patients on palliative options and try to make their remaining time as good as it can be would reduce much unnecessary suffering.