Boner Cancer in a Rottweiler

My 8 year old boy started limping on his right hind. It's amazing though.. when he's getting food or playing with the ball, he jumps and plays like he's 2 years old. The vet just called me about his X-ray and said the bone looks slightly unusual, enough that she's going to do a bone biopsy. She said that because of his age, breed, and what she's seeing on the X-Ray, that I should expect bone cancer.

She mentioned things like chemotherapy, cutting off his leg, etc. I am not going to put my boy through any of that. What I wanted to find out from you guys is, for those of you that had a dog with bone cancer (perhaps specifically of the leg)...

1. How rapidly did it get worse?
2. Did you treat, and what did that involve and cost?
3. Did you put the dog down once you found out about the bone cancer, or did you wait for them to be unable to walk or be in visible pain? At what point did you put your pup down from bone cancer?

I'm pretty devestated and hoping that I "win the lottery" and she says it's not bone cancer in a week when the biopsy comes back. But she did say to expect bone cancer, and now I just need to figure out what y'all do and have done in this situation. Please comment from a place of "here's what I did / experienced"...