Your situation mirrors mine; cancer directly over the heart. Only full doses of radiation are recommended for me, and I have continually said, "No", which really antagonizes the surgeon. Without radiation, the surgeon will only preform a radical mastectomy, even though I have had two surgeries last year (1. lumpectomy+ and removal of lymph nodes; 2. tissue removal on the heart muscle to achieve clear margins). If I agree to seven weeks of radiation, he will "snip" the current tumors which appeared along the lymph node incision, and I will save what is left of my breast. I have been warned of a possible heart attack.