Liz, it sounds like you are in a very tough and serious situation. I second Gary and David's advice. Being a caregiver to a person with cancer is a different ballgame than trying to save someone from alcoholism and addiction. One you can be helpful, the other is completely up to the individual. Our only responsibility to those with the disease of addiction is to be available when they come for help. No he probably isn't in his right mind either due to fear, depression, or drink. Here's the thing, he has to address the first issue and that is sobering up to make rational decisions. If not his efforts at cancer treatment will probably be futile. No matter what anyone thinks this is the cold hard truth. The desire to fight has to come from within, and is boosted by those who love and care. If we choose to not fight it is our choice and no one should feel guilty.
We can't live for others, if we could there are many here that would've done that. This case is bitterly sad because of the difficult fights we have all read about lately. But, the bottom line is it's his choice. If you pray, pray real hard for him, and be there if he asks for help. If he calls for a ride to the hospital, take him. That is clearly where his next stop needs to be. They can treat both of his ailments safely then maybe he can find treatments for them and get on with his life. Good luck to you. Lee