"I was under the impression that cancer spreading to the bone was not good news."
My understanding as well. I've heard it is also very painful.
Very sad. Prayers and may God grant them strength.
Based on the experience of those near and dear to me, breast cancer in this stage is pretty much a crap shoot. Until they have a clear metric on precise type and level of aggressiveness, there isn't much that can be offered in the way of a prediction. This is going to take some further study. The diabetes analogy is usually fairly accurate.
And... there's an amazing amount of research in chemo going on, some of it with quite encouraging results. So I think the only thing you can say with certainty is, "we'll see".