My surgeon based the decision regarding radiation on the "grade" of the cancer. I too had clear margins, and no lymph node involvement, but when it was determined to be a "high grade", it was a no brainer. If "Intermediate grade", which they originally thought, I would have had to make the choice but at "high grade" this made the decision easier, I didn't even have to think about it. I don't see anything in your post regarding grade??