You need a second opinion. Frankly, my experience with Mayo has been mixed. My urologist was sharp, communicative and honest with his opinions. My radiologist was almost the opposite. If I didn't ask the right questions — or any questions — I was unlikely to get all the information I needed to consider my options. Mayo will "sell" you on Proton therapy because they have $100's of millions of dollars invested in the equipment. The reality is that there is no clinical proof that it is superior in any way to most conventional forms of radiation therapy. As my Mayo surgeon said to me, "Radiation is radiation no matter the source." And, yes, 18 months of hormone deprivation therapy would be brutal at any age and, in your case, being younger and very healthy, you're looking at major lifestyle changes that could be difficult to live with in my opinion. Perhaps you're adverse to surgery? If so, you may wish to re-consider. If you visit the Harvard Medical School site you'll find a very comprehensive and up to date guide on prostate cancer, including a detailed look at all options and even some references to clinical trials using alternative therapies. It's available for purchase and download at a nominal price. Well worth reading . . .