You do know dying from cancer is a long, extremely painful death, right? They will die anyway, one path cuts the pain and lets them have a proper goodbye, the other is extreme agony as their loved ones watch them wither away in pain.
We can't save people now using technology that has not been discovered yet, that's not how any of this works.
I'd wish you had stage 4 bone cancer so you can tell what pointless chemo rounds and / or dying from slow organ failure feels like, but I'm not that kind of person. I do hope both sides of your pillow are warm tonight, however.
I wished both sides of your pillow were warm, there are worse things in life, like stage 4 bone cancer and being unable to end your suffering at your own decision.