This is absolutely how I feel. I may not take this kind of treatment in the early stages of the disease, but as soon as feel that I might be losing myself, I'd roll the dice without blinking.
It's hard to describe unless you've watched a loved one go through it.
Now, if those numbers would show something like 50% chance, that would be much better.
Different diseases / treatments cause different pain levels and suffering in those that have them and the ones close to them. Spending 3 months next to your loved ones or 6 months in a hospital bed is a heart-breaking decision to make. The ability to manipulate the probabilities regarding how one's diseases progresses is the most basic human right that an ill person can have. I really hope you're not advocating taking that liberty away from them.