My husband has the same cancer, Stage 4. We were told that for his case IMRT would have a better chance for a cure. We had really hoped to do proton for the reasons you cited. I believe in our state insurance cannot deny proton therapy. Not positive because we did not investigate thoroughly the payment once we made the decision to go with IMRT. I will say I have had no luck budging our insurance company on things that made mo sense to me to deny. Even when we explain how it has the potential to save them money, they seem stuck on their current criteria. It is a frustrating cycle. I wish you the very best in your quest.