If you use proton radiation, there is no damage to heart, lungs or any other part of the body. Google it! There are now many proton centers throughout the country. I had 16 treatments after a mastectomy and 6 nodes removed (3 positive). My surgeon and I agreed to leave the remaining lymph nodes alone if I would agree to be treated by proton radiation (Mayo Clinic in MN). I never had lymphedema as a result!!! I am 83+ and doing very well. Tamoxifen somewhat nasty but I have adjusted to it pretty well. Surgery/radiation in 4-5/21. Onco-type DX score was 6. Good luck and go Proton!!!