I understand what you mean Avatar, and i've asked the vets about it. I read all about it here too, to be informed and not have it done wrong, and tried to prepare myself to it in case it would be necessary. But the vets answered that when it's time for it, they'll be the ones telling me.
The treatment is working for the first time in months, and if only he can stop losing weight (and we seem to be on the right track) we have a good chance going on here. With the pain meds, he isn't in such pain anymore, and the proof is that he doesn't even scratch himself as he used to. Things are working for the first time. Let's give it some time... if he gets worse, i'll be the first one not standing to see him in pain.