Beau--Hypatia lost her mom to lung cancer ~12.5 years ago, about six month before we were married. Her mom had already had a 2-3 year struggle with it when I met Hyp, and I was with her the night she got the call that the cancer had metastacized to her mother's brain. So we know the fear and pain you're going through.
But with hope, prayer, luck, modern science, and sheer determination, it's doesn't have to end that way for you mom. Not by a long ways. And you have the heartfelt prayers of some very good people here, some of them among the finest I've known, going out with the hope that your mother makes it through this--especially from those of us who have lost someone to cancer.
Add mine to them, for whatever it's worth. At tomorrow night's Taize service, every note I sing and my every moment of silent contemplation will be dedicated to you and your family.
Christopher Hoover