When I had my lump in the remaining breast, the onc told me she didn't think it was anything, I'd just had a mammogram and it was clean (Of course, I'd already had two cancers that were missed on mammogram, so that was little comfort). I went to my surgeon. He didn't think it was anything, either. However, he then added, "I think you've heard that before, though, and it turned out to be cancer. So let's just go ahead and do a biopsy." Let me tell you, there is great comfort in that little scar that got me a "benign" dx! And I'm so glad he didn't object to doing a biopsy, because that was the only thing that would have assured me that it was "nothing."
I didn't have radiation, but I guess it can cause all kinds of changes in the structural tissue of the breast. But if you're doing breast exams and know your breasts, I would think the doctors would listen if you tell them something has changed!
"There's a difference between a philosophy and a bumper sticker." --Charles Schulz