I agree with the above - proton is supposed to be way less radiation to the heart and lungs. I did a lot of research on this b/c I thought I would need radiation to the left but fortunately in the end I did not. With that said, if you will need radiation on the right breast, insurance will not approve proton. Proton is way more expensive and only some ins carriers will approve it, and only if there is sufficient reason to show that left breast regular radiation would damage the heart and lungs. If you are trying to do proton for the left breast - there are only a small group of places in the country that do it. Its very important to find a place with updated machines AND lots of experience, b/c there is way less room for error with proton than regular radiation. Northwestern Medicine in IL was one of the very first to offer proton, so lots of experience, they're a top notch cancer place. Of course Mayo MN (altho surprisingly they started proton after Northwestern) is also great. If you need to get more info - call https://www.floridaproton.org/ . They're also highly rated, lots of experience and service the Mayo clinic cancer patients in FL. Explain your situation and they will provide helpful info about what you may or may not qualify for, etc. Good luck in your treatments, sending positive thoughts you find and receive all the treatment you need.