If you have radiation, you cannot have surgery later. My daughter went thru the same thing. She had all cancer removed first then the radiation because that is what she was told. It has been over 7 years ago. All is still clear. We won.
I can understand your wanting every bit of cancer removed from your body, but the internal mammary lymph nodes apparently can be very difficult to reach.
I think you should discuss this with your surgeon, and see if s/he feels it would be possible to remove the additional mammary lymph nodes. If this is not feasible, then
let's hope the radiation "kills" any possible remaining malignant cells, and that the Herception keeps any form returning.
Best wishes...