This is for you, Ed. Gonzo made a good point about the benefit your data point could be to the future of cancer research, but this is your time now and that's more important than one data point. Decide what you want and don't let cliches about fighting the good fight convince you to do what you don't want to do. Live the rest of your life your way, whichever way that is.
Here's a powerful article about end of life issues. It's been posted here before so you may have already read it. But if not, here you go:
How Doctors Die