Yes if your Dr feels that one treatment is not working then it is not unusual for them to try something else. My Dr has told me that there are hundreds of drugs out there that we can try so not to worry, and I don't. He has done a good job of keeping it under control for 3 years now that I trust he knows what he is doing.
None of us looks at our chances of survival. As you know there are women out there who were just given months and are still here years later. We all know that we have the same chance of being in that percentage that beats this things as is around for many years to come. If there is only 1 out of 10, you have as good a chance as any to be that 1. so never give up hope.
Chris
Only you can make the decision on what is right for you. If your doc say's the chemo isn't working then by all means try something else. as for what your survival chances are. no one knows that. I've seen people given 3 months to live and have lived for years beyond and i've seen people given a great prognosis and die within a months time. One thing is for certain though, live your life to the fullest, live every day as if it were your last.