Earlier quoted context omitted.
Making the immune system target tissue produced by the body, even a cancerous growth, is risky business.
Even if that statement were correct what difference does it make if you're going to be in the ground in six months?
The difference between those 6 months being a slow grind that gives you the chance to say goodbye to the world vs. sudden onset death from overwhelming immune malfunction. Quality of life is not an afterthought, even with the end in sight.