The point is not survival rate, it is the contribution of chemo to survival. Many cancer sufferers survive for a long time by doing nothing. Chemo therapy only adds a couple of percent to the survival and that is only after they deduct the patients that chemo outright kills. I have know people who had a normal chance of living a year or more if they did nothing but were dead in three or four months after ONLY one round of chemo.
The point is that when it comes to either survival rate or quality of life, chemo is an extremely poor choice.