I just read your post and I cannot believe how selfish and foolish your friend is. He is putting you and probably everyone who cares about him through hell because he is too afraid to quit smoking and get treated. He apparently cares more about that than anything else. It's a shame. He says he doesn't want to get disfigured, well without treatment he is guaranteeing that he will. His demise won't be pretty or fun for anybody, especially you as his caregiver. I know we all have the right to decide our own fate and course of action when we get sick but if you care about your loved ones you will consider their feelings in your decision.
I was diagnosed last year with Stage IV cancer in my tonsil and underwent radiation and chemo. I couldn't swallow and ate through a feeding tube for 6 months. I had to relearn how to swallow. It wasn't pleasant but it's over and I'm alive and well for now. Whenever I didn't want to go through anymore I just thought of how it would hurt my wife if I gave up. I'm glad I stuck with it and although I'm not exactly as I was before (but pretty close), I appreciate what I've got and look forward to the future.
To answer your question, it sounds like the cancer is metastisizing which would probably make him a Stage IV (at least a III) . It depends on where his cancer spreads as to how long it will take. If it goes to his bones he will start having alot of bone pain and fractures. If it goes to his lungs he will have alot of pain and will lose the ability to breath. If it goes to his brain...well you get the picture. He is choosing the most painful, disfiguring, and hurtful way to deal (or not deal) with this. My sympathies are with you. Keep up your strength, you're going to need it.