Jon! I'm so sorry. I've had two Grandma's that have had to been taken of life support becuase their cancer was so bad that there was no hope. I know what you're going through. My best friend's mom was able to beat breast cancer a few years ago, but not everyone is so lucky.
Just remember. God has a plan for everybody. People go when it is their time. If anyone completly heals, it means he did not need them back. He has a task for her that is more important now. She is in a better place, and best of all, pain and cancer free.
H-D