Thank you for the additional information. For this iguana, I think it's been a bit of luck as well. I've made plenty of mistakes and just sort of stumbled along (ended up with him when he was 2 weeks old quite by accident). The Ultimate Iguana Guide (http://www.amazon.com/Green-Iguana-Ultimate-Owners-Manual/dp/1883463483) was a really useful book.
I have CNAs and nurses in the family and have received many lectures on what they have seen in human land. I am trying to apply the idea that it's more important for his pain to be eased, and that he shouldn't have to live miserably due to medical issues (lizard nursing home??). I think I'm okay with this being end of life. I'm not okay with him suffering needlessly.
I'm going to talk to my vets more just to ask some additional questions. If it really seems to them that we're really talking cancer, then I might stop treatment. The amount of pain a surgery causes a reptile isn't worth 2 months. He would spend a lot of that in major pain. I've always been told there are no real painkillers for reptiles, and he's been through surgery before (neuter, removal of damaged hemipene, and tail amputation). I wouldn't do that unless we're talking around 6 months or more of additional pain-free life.
Again, than you for talking to me. I know veterinarians or even tech often don't have the extra time for a lot of discussion. I work in IT, so I get a lot of "magically fix my computer for free and in 5 minutes." I see the same thing happen in medical and legal fields.