In terms of that, obviously a patient doesn't have to accept treatment that they don't regard as acceptable, but it shouldn't very well be, in my view at least, a sufficient basis for seeking assisted suicide or euthanasia. There is treatment available to someone, potentially treatment that could cure their condition. They just decide that they don't want to go forward with that.
It's their option to refuse treatment, of course, but to say that someone doesn't want to have their suffering alleviated in a way that the medical system can alleviate it, that their desire not to have it alleviated is a sufficient basis for allowing them to access this, at that point you might as well allow anyone to commit suicide legally.
It doesn't make sense to me that the desire not to have your suffering alleviated is a sufficient basis for accessing the service.